This was incredibly unique, gripping, and exciting. It felt very much like reading a TV show, which could be quite fun but sometimes fell a little flat. Despite that, the concept was super entertaining. Overall I enjoyed the different timelines but definitely liked some more than others.

Thanks to NetGalley and the publisher for this ARC!

5 stars

What if there was an otherworldly repository of people's memories that could be accessed through the use of a watchmaker's ingenuity? Who would you want in charge of maintaining it, or deciding whether or not certain memories were retained or destroyed over time? That is the premise of this far-reaching story about two young women and their individual relationships to this ethereal library. As you get further into their dual timelines (bouncing between pre-World War II Germany and Cold War-era USA), you start to realise just how intertwined everything truly is, and how these two disparate timelines aren't quite so separate after all. Science fiction meets romance meets history in this page-turner that I couldn't put down.

This book really reminded me of Matt Haig's "The Midnight Library" with the setting of an alternative universe-type library/repository of humanity's stories, a.k.a memories. As well, the novel was so beautifully rendered and the heartache was palpable in certain sections. It's a richly told tale of the enduring power of love, memory and sacrifice, and how time and truth may not actually be as linear as they once seemed.

Thanks to NetGalley, author Hayley Gelfuso, and Atria Books for giving me access to a free digital ARC of this book to read and review. All opinions are my own and are provided here voluntarily.

I loved this book – I thought the story, pacing and (most of) the characters were great. This story follows multiple POVs and time periods but ties together beautifully. We are first introduced to Lisavet, a young girl who is stuck in the timespace while waiting for her father to return for her. She finds books that hold the memories of the deceased, but quickly learns that there are timekeepers who destroy these books in order to control history (and the future). We are later introduced to Amelia, a young teen who is mourning the death of her uncle, when she finds herself involved with the CIA as they try to find a valuable resource in the timespace. I felt every emotion while reading this book and the way everything tied together was beautifully executed. Thank you NetGalley and Atria Books for this eARC.

**spoiler alert** This review is based on an Advanced Reader Copy (ARC) provided by NetGalley in exchange for an honest review This review may contain spoilers.

It took me a little while to get into The Book of Lost Hours, but I’m so glad I stuck with it because by the end I was completely pulled in. The opening threw me at first—we start with one character and then quickly shift into another storyline, and I honestly thought I might have missed something. It takes quite a while before the first thread returns, and in those early chapters I kept questioning whether I was supposed to be following the same person. Once I got my footing, though, the narrative really started to click.

What struck me most was how layered this book is. It’s not just a historical novel, and it’s not just a story about magic—it’s both, plus so much more. I loved the way the historical elements and political maneuverings worked in secret, the rest of the world none the wiser to the magical happenings. The multiple timelines were also handled in a way that felt purposeful rather than gimmicky; every shift in time added another piece to the puzzle and deepened the emotional resonance. By the time everything wove together at the end, I was impressed by how seamlessly it all fit.

While I did manage to guess most of the plot twists before they happened, it didn’t lessen my enjoyment. In fact, they were exactly the turns I was hoping for, so when they came, it felt rewarding instead of predictable. I especially enjoyed the romantic thread running through the book—it added a softness and humanity against the backdrop of espionage, secrecy, and high-stakes tension. The secret-agent intrigue paired with the purposeful magic of the time space made for a really unique and memorable reading experience.

Overall, The Book of Lost Hours is a rich, atmospheric novel that takes some patience at the beginning but pays off in the end. Readers who enjoy intricate historical fantasy with political layers, multiple timelines, and just a touch of romance will definitely find something to love here.

Thank you to NetGalley for a free ARC in exchange for my review. Despite, my feelings are my own.

I'll admit this one sat on my ARC shelf for a bit - until I read about it elsewhere and thought "That seems interesting" - only to realize it had just been released. So happy release!

In the first 20% I struggled to keep the characters straight and to figure out where the book was going, and to understand what was happening in the Time system - but then, it grabbed me and I couldn't get enough.

The more I read books about time travel the more absolutely fascinated I am by it - and, also, fully terrified.

The connections of the worlds and timelines - the relationships of the characters- and the twists the story took - and the atmospheric environment - were all absolutely captivating. I found myself sneaking moments to read just one more page between tasks - and thinking about the book non stop.

Super impressed. I'll be thinking about this one for a long time.

This was such an interesting read! I loved the idea of this book, but got a little confused here and there. I think it was fun and refreshing & if you love this genre, then you'll love this book.

Hayley Gelfuso's The Book of Lost Hours is one of my favorite books of the year. It caught me by surprise how much I loved it, but, even after finishing it over the weekend, I can't stop thinking about it, about Lisavet Levy trapped inside the time space, traveling through the memories of others, guided by the the specter of Azrael. I didn't so much read The Book of Lost Hours as much as I inhaled it, absorbed it, and sobbed when it was over, All the stars.

This time-travel fantasy jumps between World War II Germany, Cold War-era U.S., and a magical library that catalogs time itself. Those who seek to change history tamper with the library's artifacts, leaving fractured realities behind. If history is written by the victors, "The Book of Lost Hours" is what was left on the cutting room floor. This historical fiction explores alternate timelines, imperfect memories, and questioning reality itself.

The Book of Lost Hours is good for lovers of historical fiction and magical realism. This one started a little slow but about a third of the way through it picked up. This novel offers a creative take on time and choices. If you enjoy atmospheric, slightly surreal storytelling, this book might be for you.
Thanks to NetGalley and Atri books for my ARC of this book.

I was intrigued by the dual timeline, the time space, and the romance. The exploration of time, memory, truth, sacrifice, and love are compelling elements in this lovely tale of Lisavet, Ernest, and Amelia. I look forward to recommending to fellow readers who enjoy books like The Midnight Library.

I’ll start with what I loved which was the atmosphere of this book. The world building. Loved it. Unfortunately, I could NOT keep up with timelines and new characters - I was really confused which left the characters connection lack luster. I really loved the idea of this and the prose.

What a stunningly beautiful debut!
This story reminded me a lot of The Midnight Library but still felt completely unique. The idea of a library built from human memories? 😚👌🏼 so good! This one was everything with magical realism, time travel, historical fantasy and even a touch of romance.

The writing was lyrical, the characters unforgettable and the story will leave you thinking about the power of remembering and thinking of the sacrifices we make for love.

An incredible debut that deserves all the hype. 🤍

I actually loved this. while the beginning was a little bit slow. I absolutely loved it once it started to pick up. the plot twist, the world building. it was amazing

knew this was a book to read months ago after a friend read an ARC. I immediately requested it and was so excited when I was approved on NetGalley. This book very much feels like Addie LaRue and the Midnight Library. The story follows two timelines, one starting during WW2 and the other starting in the mid-60s. Lisavet finds herself trapped in the time space where her father did her from the Nazi. When he doesn’t return, she lives among the books of memories and works to save the memories being destroyed by world agents. Amelia, lost after the death of her only family, her uncle, is recruited by the CIA to find a book her uncle was searching for. We discover along the way that time is tricky and is not always straightforward and linear.

I really enjoyed this book. It has the perfect amount of magical realism and historical fiction with all the tragic heartbreaking you can ask for.

First thank you NetGalley and Atria Books for the e-ARC!!
I really really wanted to like this book. I was very excited to get this , I usually love these types of novels.
I just couldn't connect to the characters. And I didn't care for the back and forth in time thing.
This book has very good reviews, but didn't cut it for me.

This is an emotional roller-coaster. There are some fun twists in the book. Some I saw coming, but they were still fun to read. I really enjoyed the characters and the romance. the relationships in this book are beautiful.

Thanks to the publisher and NetGalley for letting me review this book. Let me just say, actions have consequences. It was interesting to see the twists and turns this book took. She does try to rectify her past as the book progresses. The lengths a mother will go to protect her family; no matter what the cost.

4.5⭐️

The Book of Lost Hours was a thrilling, emotional ride from start to finish. It's always fascinating to read how different authors take on the concept of time in their stories and Gelfuso did not disappoint. This book reminded me of another favorite book, The Book That Wouldn't Burn, as well as the TV series Dark. What a wonderful debut novel from Gelfuso. I can't wait for more stories from her.

This story was just as confusing and twisty as most time-travel [adjacent] books get. I say adjacent because while there is time travel, it's not really utilized in the same way that most usually go, it's less about time than space and it gives this story a little something different.

I enjoyed the arcs of all the major characters, they had satisfying stories and conclusions. I am a sucker for time travel and this one hit a lot of my favorite marks (lots of seemingly unrelated threads getting brought together towards the end is a big favorite and this story did that very well).

Thank you Atria books and NetGalley for this eARC in exchange for my honest review.

The Book of Lost Hours by Hayley Gelfuso is one of my favorite 2025 reads. I got this book as an ARC on Netgalley, and now I need to go buy it to own a hard copy.

This books combines the ideas that one can fall into time or a memory, similar to the Midnight Library, and also captures historical conflicts between the US Govt. and Nazis, then later the Russians and the rise of communism.

The plot takes you on a journey through time bouncing back and forth from past to present because time itself can be manipulated. There is a hint of feminism. Our lead is a woman growing up in the 1950s-60s. All Lisavet Levy wants is to protect herself, her memories, and her family, but she is seen as a threat by men in control because she is more clever, more worldly educated, more powerful, and a woman. I wanted a happy ending for Lisavet even though at times I wanted to dislike her. I was very satisfied with the ending. I left the book with a complete sense of closure.

I loved this book. I want to get lost in the time space and time walk the memories of those throughout history.

SO many thanks to NetGalley and Atria books for the digital ARC in exchange for my honest review!