by H.R. McGregor (William Morrow, $22) Long before PETA became a global force, Austrian physicist Erwin Schr�ger rustled up a koan-like riddle that became known as Schr�ger's cat paradox. He placed a theoretical tabby inside a sealed box with a capsule of poison gas that could be released only by the decay of a radioactive atom. Then he asked: Is the cat alive or dead? To determine the answer, he pointed out, one must observe the atom, which has a 50/50 chance of decaying; thus, the feline floats in a kind of quantum purgatory as long as the box remains sealed. Despite its titular reference to this mischievous scientist, H.R. McGregor's first novel has little to do with physics or felines (though a dead cat does make a macabre cameo). Instead, she serves up a Schr�ger-inspired mystery with a human body at its center. When a person disappears without a trace, is s/he alive or dead? What about an embryo, undetected by all including its carrier? McGregor poses these questions in a story that appears ready-made for the cinema: The Secret History as written by the makers of Shallow Grave. The plot churns into motion when a gaggle of students find themselves sharing a flat in Glasgow. Dispassionate Juliet, the narrator, is studying veterinary medicine; herfriend Petruchio, a depressive Italian with an impressive collection of pharmaceuticals, toils in a neurology lab. Their flatmates are all acting students: magnetic, manic-depressive Kerry; New Age-y Chris and his girlfriend Christine; and handsome, promiscuous Billy. Leading rather stereotypical student lives, these six friends share adventures, drug stashes, and sexual partners. Eventually, Kerry seduces Juliet, and the once-calm vet student finds herself entangled by her new lover's impetuous decisions and implacable appetites. When Kerry draws the attention of two posh agents who later vanish, and Juliet sees—and then doesn't see—a corpse in the coat closet, the story careens through a series of twists and turns befitting a beach-blanket thriller. Juliet's narrative plows ahead with only the tiniest bit of lyricism to remind the reader that this is, after all, a novel, and not a deposition. Her brusque style is meant to reveal her personality; she's the classic straight-person, trying to make sense of the bizarre and unexplained events unfolding around her. By novel's end, the reader's nerves are every bit as jangled as Juliet's. McGregor's twist on the cat paradox won't do much to placate animal rights activists, but it does provide a few hours of escapist intrigue.