Greta Tanner died in her sleep in the small Alaskan town of Trenton — elderly but not elderly enough to die without explanation. No medication, no known condition, no recent surgery. The town's new doctor, Dr. Grayson, examines the body and finds fresh crescent-shaped wounds hidden beneath her hair and faint burn marks on her legs. Roads are blocked by snow. Wind cuts like a blade. Something killed Greta Tanner, and it may still be in Trenton.