“I’d help you hide the body.” It’s a sentiment most of us have offered to a best friend or a sister — in spirit only, of course. In Leah Rowan’s captivating debut, Marion takes that offer and runs with it. Literally.

Marion’s life isn’t exactly going according to plan. Her career has stalled, her finances are a mess, and her studio apartment is barely big enough to hold her ambitions. But she has Lauren, her big sister, and that’s enough. Until it isn’t.

When Lauren shows up with a black eye courtesy of her husband, Marion’s world narrows to a single purpose: get her sister out. The problem is that Lauren’s husband owns a substantial stake in her interior design business, and buying him out would take more than $50,000. Money Marion doesn’t have.

Or does she?

What follows is a delightfully unhinged chain of events that begins with a desperate decision, a bus that breaks down in the middle of nowhere, and a night at a run-down motel run by one Norman Billings. If that name sounds familiar, it should. Marion is a contemporary retelling of Psycho — and if you know anything about Psycho, you know exactly where this is headed.

Except you don’t. Because this time, Norman doesn’t get away with it.

Stranded with a dead body and a dwindling timeline, Marion draws on something unexpected: her mother’s voice. A social worker who spent years bearing witness to the worst of what abusive men do to women, Marion’s mother left her daughter with a particular set of tools. And Marion is going to use every single one of them.

What Leah Rowan does brilliantly is sustain a near-feverish sense of urgency throughout. Lauren isn’t answering her phone. Lauren isn’t responding to texts. And Marion — resourceful, furious, increasingly blood-spattered Marion — is not going to let anything or anyone stand between her and her sister. The pace is relentless in the best possible way, and just when you think you’ve mapped out where the plot is heading, Rowan tosses another twist into the mix.

There’s also some wickedly dark humor woven through the chaos that kept me grinning even when I probably shouldn’t have been. This book is tense and propulsive and also, occasionally, genuinely funny — a combination that is harder to pull off than it sounds.

Mostly, though, I just really, really wanted Marion to succeed. I wanted her to get away with it. I wanted her to get to Lauren. I was rooting for her with the kind of fierce, slightly unhinged loyalty that this story is entirely about — and that, more than anything else, is telling.

Norman was her first. He won’t be her last. And I, for one, could not be more here for it.

My thanks to NetGalley and St. Martin’s Press for the ARC of this book in exchange for my honest thoughts and opinions.