On the first snowy night of winter, DI Vera Stanhope sets off for her home in the hills. Though the road is familiar, she misses a turn and soon becomes lost. A car has skidded off the narrow road in front of her, its door left open, and she stops to help. There is no driver to be seen, so Vera assumes that the owner has gone to find help. But a cry calls her back: a toddler is strapped in the back seat.