Peter Blackstone, a Denver Private Investigator, is visited by Walter Endicott, a local car dealer, and his wife. They tell him about their son, Jonathon, running off with an older woman. It isn't until Peter finds out that Walter had tried to buy the woman off that Peter gets interested. Peter starts to investigate. With each turn, he finds someone new is involved in Jonathon's disappearance. It becomes more obvious that Jonathon Endicott was kidnapped and is being used as a pawn to extort money from his father. Peter rents a place in Dillon after he discovers the woman may live in Frisco, Colorado. As he searches for the woman, he discovers that Jonathon might be aboard a sailboat called the Crystal Blue on Dillon Reservoir, a large lake west of Denver. Peter decides to find out with the hope of getting Jonathon away from those holding him hostage. He also finds that it is not just a simple case of extortion, but that it goes much deeper than that. Murder on the Crystal Blue in another Peter Blackstone mystery novel.