ONE BAD THING poses the question: can an otherwise good man commit an act of evil and go back to living his life unscathed? The story opens in the Virgin Islands. Rob McKenna is a good man who has lost much: his beloved daughter was killed the year before. McKenna's wife leaves him, forcing him to take on a crewmember, Tom Cain, to help sail the boat back to Boston. But Cain brings trouble on board and forces McKenna to make a desperate choice. «Do this one thing," Cain says. «Do this and you'll have a life.» All McKenna has to do is lie. And soon…kill.