Thirteen-year-old Caleb Weybourne is sent to spend the summer with his archaeologist father in the remote town of Chismo in northern Canada, where Professor Weybourne hopes to prove the existence of the Mahkneejosh, the legendary great lake monster of the native Ojibway people. In Chismo, Caleb befriends two Ojibway boys, Isaac and Eli, and a colourful old Ojibway man, Emmett. On a fishing trip to Red Marsh Lake, the boys encounter the violent and dangerous local fugitive, Kibo, and almost lose their lives. During their flight from him, Caleb believes he may have seen the mysterious water monster. In a dramatic showdown, Kibo forces Emmett and the boys into a cave where he dynamites the entrance, trapping them inside. Can they get out in time, or will they end their days as bones for a future excavation team to discover?