It is 1940 and a tragedy has just occurred outside Tiffin, Iowa. After a bloody collarbone, pieces of flesh, and garments are found on the railroad tracks, local police learn that Finn Fletcher, an eighteen-year-old American Indian psychiatric patient, has escaped from the hospital. Moments later, a bank in Iowa City is robbed. Without a body to autopsy, Officer Hugh Chancy has his work cut out for him. While his captain contemplates whether the two cases are related, Chancy launches an investigation starting with Finn's adoptive Finn's adoptive parents and the eventual realization that the teen was on a mission to locate his biological parents when he allegedly met his fate. His quest to locate Finn and his biological family takes him to South Dakota's Rosebud Indian Reservation and ultimately into Canadian territory, but he returns home with a trail of dead ends. As loose ends dangle, secrets are unveiled, and further leads adding even more confusion. Chancy battles his own personal challenges while attempting to solve the mystery of a missing teen trapped within something much bigger than he anticipated. Then Came the Dawn shares the gripping tale of a missing American Indian teenager and the Iowa police detective determined to find him.