Shoestring Theory is a time travel cozy romantasy about a mage traveling back in time to right some wrongs. The kingdom of Farsala is in ruins, and the once Grand Mage Cyril who stood by as it happened has hidden himself away. When his cat familiar Shoestring dies, Cyril casts one last desperate spell with his lifeblood to travel back in time to correct his mistakes and stop his husband King Eufrates from turning down a dark path. But things don’t go according to plan when a spell he cast during their wedding vows gets in the way.

I absolutely loved the first third of this book. It took several twists that were delightful surprises that I didn’t see coming and made the story feel much fresher than the synopsis suggests. That being said, I do wish that it had used that big early twist better (I’m obfuscating because spoilers) and gone a different direction with it. I guess I thought the book was setting up something but went elsewhere instead with its primary antagonist, romance, and level of coziness. It did give me a protagonist I could root for in the somewhat hotmess Cyril and his best friend Tig. I could have used more Prince Eugie pr even some PoV chapters from him.

The book is not as cozy as the marketing claims it to be, especially with the very dark tone it starts at with a cat death and Cyril killing himself to cast his spell. It does get much much lighter thereafter, but I still wouldn’t compare it to the coziness of Legends & Lattes. Neither is it as romantic as I expect a romantasy book to be. There is a friends-to-lovers-to-enemies-to-lovers romance but it’s mostly historical/off-page. Cyril and Eufie spend much of the book apart actually, so the main plot is really just Cyril figuring out how to get through the tragic events that start the domino effect of Eufie’s descent.

I did like and enjoy Shoestring Theory even though it didn’t give me exactly what I wanted out of it.

*Thank you to Angry Robot Books for the eARC via NetGalley

Thank you SO MUCH for the eARC of this book!
Overall, I enjoyed this story. I felt like at times it dragged, and sometimes I felt like Cyril's "innocence" and naivety seemed slightly unrealistic when compared to all of their experiences.

I just lost my cat and so instantly I was sucked into the possibility of bringing him back. I love Cyril's dedication to always bettering himself, as well as him and his partner learning each other and learning to communicate/be together. I think this book has SO much potential and it was very emotional and enjoyable. I loved that even though it had the essence of a cozy fantasy, the stakes were higher. The fact that Mariana Costa is an artist is a huge benefit to her story telling because she writes descriptions like a drawing: no detail is too small. Although sometimes a lot of detail can distract from the story, hers did not!!

Overall, I enjoyed this and love that more and more LGBTQA+ representation are getting their moment. Excited to see what Mariana Costa does next!!

Cyril Laverre was once a grand mage. Now, he's watched his world fall apart, and even his loyal cat familiar Shoestring has passed on. With nothing left to lose, he sacrifices himself to cast one last-ditch spell: one that will take him back in time to the beginning of the end of the kingdom of Farsala. But when he awakens in his twentysomething body again, things are awry. Shoestring is back, but he's acting more like a normal cat than a wise familiar. The wedding ring he wears around his neck has somehow followed him to the past. And Eufrates Margrave—who in Cyril's original timeline became both Farsala's despotic king and Cyril's husband—has been pulled back in time, too.

With his plans to assassinate his former lover now scrapped, Cyril enacts a mad plan to prevent Eufrates from taking the throne once again. His first goal is to prevent the death of Eufrates's sister Tigris, allowing her to marry her fiancé Atticus and take the throne. But as Cyril peers further into the weave of magic around him, he discovers that there's more to the kingdom's downfall than even he knew. More troubling still, it seems he's still madly in love with his wicked husband.

Shoestring Theory is billed as a "friends-to-lovers-to-enemies-to-lovers" romance for people who like fanfiction, but I feel this sells the novel short. For one thing, fanfic is not a monolith; for another, there's so much more to the story than its central turbulent romance. (Although, yes, that's huge and very fun.) As exciting as the broad story is, the underlying tale of Cyril's own character progression is the most rewarding part of the story. He's depressed, imperfect, and full of regrets; but even as an older man literally revisiting his youth, he has room to grow and change. Equal measures light-hearted and thought-provoking, this is a fabulous fantasy-romance with a wonderful message about finding your heart and your self-worth.

This book was far from bad, in fact, I think it was really well written. However, I just couldn't get into it. I tried, but ended up DNF'ing part way through because it just wasn't the right time for me to read it. If you like complex magic systems and apocalyptic futures, you'll like this book. But just bear in mind it is so slow.

Very rarely do I say that a story would benefit from being split into multiple books, but I'm going to say it here. This was a fun book with a lot of potential that ended up being tragically stymied by being crammed into 400 pages.

One-time Grand Mage of Farsala, Cyril Laverre, sees an opportunity to set his mistakes (and the world) to right as he nears the end of his life and copes with the loss of his familiar. Traveling back in time, he has a big task ahead of him - prevent the untimely death of friend and future-queen Tigris Margrave, and in so doing prevent the descent of Eufrates, her brother - Cyril's husband - into madness and tyranny. Except the marriage bond he once placed on them both won't make that easy.

Shoestring Theory had so much promise, but I sit here struggling even to compact the story into a workable summary. It was just so much plot to work through, even for a book that was rather slow-moving and meandering. There were just so many things that Costa had to solve, plot-wise, that cramming it all into a single book just didn't do it any favors. Instead, it felt like each event was glossed over (and not in a cozy "these aren't priority" sort of way) and I left feeling unsatisfied. The antagonist's motives felt underdeveloped, the past between Cyril and Eufrates was disappointingly scant, and their current romance was difficult to believe in how rushed it was all resolved.

On the other hand, Tig was a joy of a character and the author's way with describing the setting and outfits was lovely. The bare bones of this story had so much potential.

“No. I do not hate you, Cy. I don’t believe anyone alive hates you as much as you do.”

Well, this was cute!! Though the tone starts off dark, Shoestring Theory is a story about self love and forgiveness. The characters were flawed, but easy to root for. I’ll forgive any predictability for the cozy ending. Let’s be real, the best type of time travel stories are the ones that heal trauma! Would definitely recommend. Thanks NetGalley and publishers for the ARC!

I would like to thank the publisher and NetGalley for allowing me to read and honestly review an advanced reader’s copy of this book.

Sometimes you accidentally read a book that is just perfectly written for you: and this is one of those for me.

This is The Sins On Their Bones - But it didn’t leave me heartbroken in the end. The tension in this, the relationship between Cy and his tyrant ex-husband, the fast-flowing plot?? All of this was perfect, and I could ramble for hours about it.

Cy is a wonderful main character. I loved seeing his growth: for him to overcome his suicidal ideation and learn that he is loved by those around him.
We follow him as he, as a 50 year old man at the end of the world, performs a last ditch attempt to right the wrong of the past. (By literally going back into the past, into the body of his 20-year old self.)
He expects to meet his ex-husband before he turned into the tyrant his is in Cy’s current reality; only the spell goes slightly wrong, and Cy’s ex-husband is transported to the past right along with him.
(Yeah, I can’t spell the man’s name, I’m so sorry, I’ve just been calling him Euf in my head…)

The magic system is easy to understand, the writing style is lovely and smooth and it was honestly so hard to put down. This book is fantastic and I hope the author has more stories to tell, because I’ll be auto-buying them!

Thank you to Netgalley and the publisher for providing me with a free eARC in exchange for an honest review!
Rating: 5/5
I had such a fantastic time reading Shoestring Theory. From the first page I was hooked, delighting in the idea of time travelling to the past. The book is rather fast paced and engaging, which made for a fun and quick read. My only criticisms is that the side characters could've just been a bit more fleshed out as well as the villain. I also wouldn't call this a 'cozy fantasy' like Legends and Lattes (honestly I can't make sense of the comparison, the two aren't really alike) as the stakes are far too high, but rather cozy-adjacent.

The book starts off with exactly the kind of grim, immersive setting I was looking for. It strikes a great balance between cozy fantasy and traditional fantasy early on, creating a world that truly pulls you in. However, after a major plot twist, it takes a more juvenile turn that didn’t quite work for me. The introduction of the second romantic love interest was a bit jarring, especially since I was so invested in Eufrates and Cyril’s dynamic. The twist also made things harder to connect with, as Cyril—who is established as the best grand mage of his time—didn’t quite live up to that reputation once he goes back in time. That aspect left me feeling a bit disappointed.

That said, this is far from a bad read! In fact, the first half of the book was so rich and imaginative that it makes the second half feel less impactful by comparison. The court politics, the main couple's dynamic, and the world-building in the early chapters were all a joy to explore.

Mariana Costa has a beautifully unique writing style and brings some really interesting ideas to the table. While this book may not have fully nailed its execution, I'm excited to see what she creates next!

If you're a fan of historical romance manhwas or isekai stories, I’d definitely recommend giving this a try—you might just find it to your liking!

I really enjoyed this book! It was such a cosy fantasy but there was still lots going on and the plot was thought out really well. I loved the aspect of time travel and how Cyril had a personal journey along with the actual journey of time travel. The family aspect of this story was amazing and really gave the book a heart with real emotions that you felt along with the characters, the relationships felt so developed and well thought out with made them seem realistic as a reader. I love how strained Cyril and Eufrates relationship was but there was still so much love between them, doing could stop them from loving each other is even they had grown apart as people. The shocking revelation towards the end of the book was so good it was one of the things that made the book seems so good and stand out because you weren’t expecting to find out and for Cyril to save Tig so successfully. This book was a joy to read and you felt you could really connect with the characters because it was written in such a lovely way even though it felt simple it got across all the hard and complex emotions the characters were feeling while still being able to understand it all. I do feel it would have been better to see Cyril and Eufrates together more to really understand them as a couple but you could still feel their strong love, it just could have been backed up even more.
Overall I would 100% recommend this book to anyone who wants a cozy, easy to read fantasy full of emotion and strong family connections! I’ve already preordered mine don’t forget to preorder yours!

his is a quirky, fun, and heartfelt time travel fantasy that really surprised me. Cyril, the main character, is a former Grand Mage who gets a second chance to fix his broken kingdom and his relationship with his husband, King Eufrates. The mix of magic, humor, and emotional depth kept me hooked throughout.

What stood out most was the balance between lighthearted moments and real stakes. The character development is fantastic, especially between Cyril and Eufrates, whose relationship goes through so many layers of tension, love, and regret. There are also great supporting characters, like Tigris and Cyril’s cat familiar, Shoestring, who add warmth and humor to the story.

If you’re into time-travel romance with a bit of magical mischief and enjoy strong character-driven plots, Shoestring Theory is a must-read! It's a perfect blend of cozy fantasy and high-stakes adventure.

"Shoestring Theory" is a delightful second chance fantasy romance featuring two bitter exes stuck reliving the early parts of their romance in a time travel mix up. That's probably a lot to take in! Don't worry, it's easy to get sucked in to this one - the characters are charming, the romance sucks you in, and I really enjoyed the side-plots. Cyril is a wonderful main character - angry but sympathetic. Even as you want to yell at him, you understand where he's coming from.

Disclaimer: Shoestring Theory is being marketed as a cozy fantasy - and it's not that. It's a wonderful book and I enjoyed it, but it has several trigger warnings readers will need to abide by - wanted to be very clear about that.

Thank you to Net Galley and Angry Robot for the ARC. The concept sounded cool but the execution was a let down. It was difficult to care about the characters and the beginning was surprisingly slow.

Thanks to NetGalley, Angry Robot and Mariana Costa for this ARC.

This book read like a warm hug. It was quite difficult to get into it for me, it being slow paced in the beginning, but once I got into it I could not put it down. I loved the characters, their interactions, the conflict, and the romance is dashing. It is very quirky and a fun read. This book is very cozy, and at the same time it has some plot twists that keep you on the edge of your seat, when you get to them. I enjoyed the writing style as well.
That being said, I expected this book to be 5 stars for me, unfortunately it was more like a low 4 star read. Still it was a good experience, and if you're looking for cozy fantasy this one's a good pick.

Also I think this book would be great in audio format (for me personally, I find it more interesting to listen to slow paced stories.)

SHOESTRING THEORY - MARIANA COSTA

It took me a little while to get into this particular story, but once I was in, I was IN. With a set of characters that are loveable and memorable, I think Shoestring Theory is one of those books that gently woos you and then you can't imagine a life where you haven't read this special tale. Here's a synopsis:

The kingdom of Farsala is broken and black clouds hang heavy over the arid lands. Former grand mage Cyril Laverre has spent the last decade hiding himself away in a ramshackle hut by the sea, trying to catch any remaining fish for his cat familiar, Shoestring, and suppressing his guilt over the kingdom’s ruin. When Shoestring wanders away and dies one morning, Cyril knows his days are finally numbered. But are there enough left to have a last go at putting things right?

Time travel, a unique magic system and a very fun take on friends to lovers to enemies to lovers - these are just a few of the elements that make Shoestring Theory such an enjoyable read. One of my other favourite aspects of Mariana Costa's storytelling is that we find out information in real time along with other characters, and this places the reader right in the middle of the action.

Although the book is marketed as being similar to Travis Baldree's Legends and Lattes, and certainly reads like a cosy fantasy in places (especially when it comes to the characters), the stakes feel a lot higher, which makes sense in this context! After all, the fate of a kingdom is at stake - along with a romantic relationship or two.

The storyline often changes direction and takes you to unexpected places, which kept me guessing right until the end (which is SO good). And while all the characters are lovely, I adored Cyril the most. A true underdog hero, he is self-deprecating, anxious and full of doubt, which makes him endearing and oh so relatable. 

I'm not sure if there is a book two on the way, but if there was, I'd jump at the chance to dive back into this world! Thank you to Mariana Costa, NetGalley and the publisher for my copy of this ARC.

Release date: 8 October 2024

Review score: 4/5

TWs: Violence, blood, d*ath

3.25 stars

Shoestring Theory was an interesting cosy fantasy and I don't think I could rate it more because while I liked the concept and the characters, the plot was quite slow and this just didn't feel like it needed to be as long as it was. I guess that is why it is a cosy fantasy and not something that can be prolonged the same as the fantasy novel length of pages while maintaining interest and excitement.

Some of my excitement drained the further along I got in the story just because I feel like the characters could have been developed more especially with a cosy fantasy where there is not a high stakes fantasy plot, the characters need to carry the story and while main character Cyril did, Eufrates could have been utilised more because in the moments he did have, he shined!

I wish we saw more of their dynamic and not just little glimpses because they have years of history going further than their marriage we could have seen in flashbacks. This with added moments of Cyril doubting his view of Eufrates and his actions through a rose tinted love lense could have been exciting.

I feel this book lacked some of the moments of shared history which were critical to their story and current tension of Eufrates' path of choosing evil and being a coloniser. If Cyril had doubted his relationship and believing Eufrates was morally grey then it would have made for more drama and complex storytelling before the big reveal. I did like this but was hoping for more bite to enjoy Shoestring Theory.

Thank you to NetGalley and Angry Robot for an arc in exchange for an honest review.

This is a time traveling mage story with animal familiars, court politics and found family. It has some strong female characters in Tigris and Aunt Helene. The main character Cyril begins as a guilt ridden mage that determines that he is going to attempt to set the kingdom right by changing the past.

I enjoyed it overall for the interesting magic and familiars but also found it to be somewhat slow and a bit dark at first. It is light on the fantasy and the romance and is more character driven.

I was given a copy by the publisher via NetGalley (thank you!) and all opinions are my own.

Mariana Costa's "Shoestring Theory" is a fun, modern story that mixes science, humour, and heart. Two physicists who couldn't be more different—one realistic and grounded and the other impulsive and spontaneous—are forced to work together on a new research project. As they deal with problems at work and their growing feelings for each other, their different personalities lead to smart banter, tension, and undeniable energy. There are a lot of science references in Costa's smart, slow-burning romance, which makes it a fun and interesting read for people who like stories where opposites meet.

Shoestring Theory begins when former Grand-Mage Cyril decides to go back in time to stop his husband and king, Euphrates, from ascending to the throne. He sends himself back to a time before Euphrate’s coronation or madness and the death of Tigris, Euphrate’s older sister. However, his plans quickly go awry when he discovers the true power of the spell he cast on his vows, tying him and Euphrates together in that life and the next.

This story was a very charming and enjoyable read. This book is marketed as a cozy read, which I do agree with-- the tone of the book leans towards being lighthearted, straightforward, and never takes itself too seriously. That being said, the stakes of the plot are high, making it a really fun reading experience. Where this book really shines is in its character building: Cyril, Tigris, Euphrates, and Cyril’s auntie Helene are all compelling and complex characters, making explorations of the relationships between them really interesting. Their decisions, good and bad, always feel earned, even if you don’t always agree with their choices. While some pieces of the plot are predictable, it’s always fun to read simply because the characters are interesting to read about. Also, I found the simple magic system really refreshing, as it gives the author enough interwoven pieces to build a plot where magic is a key element without ever feeling pedantic or overwhelming.

I would suggest looking at the trigger warnings from other reviewers before reading. The elements listed are not dwelled upon by the book as they are much more plot elements to drive the story forward than they are reflections on these themes themselves.

The one note I would give is that the synopsis markets this as a romance, but the part of the romance that has people truly romantically involved is a small percentage of the book. The characters talk about romance a lot and spend a lot of time reflecting on the relationship between Cyril and Euphrates in a way that worked well for me but that I could see being more disappointing for someone looking for a strict-sense romance. This didn’t detract from the book for me, but I could see the synopsis misleading some readers.

I would recommend this book to anyone looking for a fun and lighthearted time travel fantasy with romance elements and compelling characters. I enjoyed my experience with Shoestring Theory a ton!

Thank you to NetGalley and Angry Robot for providing me with a digital advanced reader copy of this book! Please note that these are my thoughts on an early version of the book.

The time travel mechanics at the heart of this book have a very clever conceit that makes for an intriguing unfolding of the plot. The title is cute (a pun on one of the character's names) and hints at the many twists and turns this book will take the reader on. Overall, I found the book to be incredibly well-written and liked most of the central characters and how their stories wrap up neatly at the end.

However, looking back at my time with this story as a whole, I have very conflicting feelings and have to say that I did not enjoy most of my reading journey with this one. Light spoilers ahead:

The book is billed as a "time travel romance" and a "charming fantasy tale" when in fact the central relationship at the heart of the book is portrayed as extremely toxic for half of the book with one character literally fearing for their life after every interaction. This left me so on edge that I kept seeing red flags everywhere (which turned out to be validated) and considerably detracted from my enjoyment of the plot. Without giving too much away: The toxicity is explained away in one way or another by the end, and things end on a positive note for everyone, including the main character who finally realizes their self-worth.

I enjoyed the author's writing style and will surely read more of her work in the future, but the ARC version of the book also left somewhat of a bitter aftertaste, unfortunately. I really did want to like this a whole lot more.