I became intrigued by Daniel O’Malley’s debut novel, The Rook, when Time book critic Lev Grossman raved, more than a month before the book’s release, that “this aging, jaded, attention-deficit-disordered critic was blown away.”

Indeed, The Rook is great, rattling fun, as if Neil Gaiman took Buffy the Vampire Slayer and crossed it with Torchwood.

It starts with a bang: Myfanwy Thomas awakens in a rainy London park, surrounded by a ring of dead bodies, all wearing latex gloves. She has no idea how she or the corpses got there. In fact, she doesn’t even know that she’s Myfanwy Thomas, because she is suffering from amnesia and remembers nothing about herself.

Myfanwy is a Rook, a junior-level member of the Court, an elite group of eight super-powered intelligence agents. The Court runs the Checquy Group, a British agency on Her Majesty’s Hyper-Secret Service, so powerful that it makes MI6 look lame. In fact, Myfanwy learns, “The Court answers to the highest individuals in the land only, and not always to them.”

Myfanwy discovers everything about herself from a dossier entrusted to her by “the original Myfanwy Thomas,” the person she was before she lost her memory. Her amnesia was no accident: One of her mysterious colleagues on the Court, she learns, is a traitor who wiped her memory and now wants her dead.

In the meantime, Myfanwy must step back into her own life and relearn everything about being Rook Thomas, all without anyone finding out what has happened to her. Her own life is anything but normal, because the Checquy Group is always on the lookout for monsters. One can never be too vigilant, since “Checquy statistics indicate that 15 percent of all men in hats are concealing horns.”

Thanks to the Checquy, Britons are blissfully unaware that supernatural forces constantly threaten the United Kingdom and the Commonwealth. (The Checquy’s American counterpart is called the Croatoan, a little in-joke that is never explained but which students of American history will immediately get.) The worst of these threats to the U.K. are the Grafters, who come from Belgium, a mild-mannered nation that O’Malley manages to render extremely sinister.

Throughout a rip-roaring narrative, O’Malley off-handedly weaves deadpan humor. As a Rook, Myfanwy is more paper-pusher than field agent, and her job lacks glamour: “There’s a reason that there’s no TV show called CSI: Forensic Accounting.” She always gets stuck with tasks like “figuring out why the hell a two-door wardrobe in the spare room of a country house is considered to be a matter of national concern.”

But crises loom, duty calls, and Myfanwy soon finds herself using her own superpower to battle horrid Belgian monsters — at least whenever she isn’t “laboriously penning formal invitations to the members of the Court to come dine at the Rookery tonight before observing the unbelievably magical amazingness of the United Kingdom’s only oracular duck.

“Of course, I couched it all in slightly more impressive terms.”