"Where the hell had the kid found a human skull? McNab heard an intake of breath behind him as someone else made out the shape in the torchlight. A metre away now, McNab crouched on a level with the child. "Where did you find that, Emma?" he said softly. She stared at him. "I was lost. I heard them calling me."" When Claire regains consciousness after a stranger causes her car to crash in a snowstorm, she is frantic to discover her nine-year-old daughter Emma missing from the back seat. Then Emma is found in the woods nearby, unharmed but cradling a child's skull. She claims it "called to her"--and she can hear another voice nearby. Meanwhile, forensic scientist Rhona MacLeod is trying to discover the identity of a corpse found badly burned in a trash bin. The body is wearing a soldier's ID tag, but DNA tests show it's not him. When DS Michael McNab asks for her help identifying the remains Emma found, they discover the two cases are linked in ways they could never have imagined.