Northwest Angle by William Kent Krueger Book 11

Cork O’Conner and family are vacationing on a houseboat on Lake of the Woods, a massive waterway that crosses the U.S./ Canadian border. But trouble follows. A massive storm front hits the area, separating the family. Caught in open water, Cork is swept from the boat. Jenny takes shelter on a small island. When she explores the island, she finds a murdered woman and an infant who has been deliberately hidden, possibly from the killer.

Cork needs to discover the secret behind the child and who wants to kill both it and its mother. With multiple suspects, Cork needs to grow eyes in the back of his head. This is another tremendous mystery by a Master.