Only Murders in the Building meets The Swifts in the first installment of this cozy whodunit mystery series.

Most people would kill to live in a glamorous New York City high-rise on the Upper West Side. Not Casey. She hates her daily morning elevator ride to school. Why? Because she's forced to stand shoulder to shoulder with her two ex–best friends, a way too bubbly new girl, and a very chatty old lady named Grandma Williams. Who cares if Grandma Williams tells hilarious stories, or if the bubbly new girl wants to be besties? Casey doesn't want to be friends with anyone—she already lost two of them. 

But things on the Carlton Towers elevator start to get strange. One of her ex–best friends bursts into tears and admits that a family heirloom has disappeared. Wallets and jewelry start vanishing into thin air. And then, the worst happens: Grandma Williams goes missing.

It seems like there's a thief—and a kidnapper!—on the loose. And the girls on the elevator soon realize that they are the only ones who can stop the dangerous criminal before it's too late.