"What's the worst thing you've ever done?" That's the question, posed by a stranger, that 41-year-old Kate Cypher can't get out of her mind in McMahon's impressive debut. Thirty years ago, Kate's best friend, impoverished and shunned Del, was murdered in the Vermont woods. Her killer was never found, and decades later the town believes Del's ghost still haunts them. But when another young girl is murdered in a copycat crime, fingers point at everyone from Kate's Alzheimer's-afflicted mother—who seems to be channeling Del's spirit—to Kate herself, who has returned home from Seattle to care for her mother and who harbors her own dark secrets. McMahon's gift is the deliciously twisty way she subverts all your expectations, keeping you guessing with wry wit and feverish chills. "The dead can blame," one character says. And the truth, this whip-smart novel reminds us, can break your heart.