 Mark accepts a friend s invitation for a  free  cruise splitting the medical duties with Jesse and Amanda. Barely aboard they must save multimillionaire Robert Brantigan who got a triple dose ampule of insulin. Jesse and Amanda drawn in patients, especially after Mark is talked into filling in for the injured activities director. Steve learns Roberts daughter from his first marriage Tracy deals in pharmaceuticals. His wife Clare manages to drug Robert and knock him overboard unseen; she tells Mark he was suicidal and drunk before the corps is found, then accuses his daughter Amy, who confides in Steve his bitchy behavior was because of a brain tumor he told nobody else. Amanda s autopsy proves murder, and the LAPD identifies Clare as the widow of rich Carl Donahue who died on another cruise, but she says not to be in the will- however his sister tells Steve she was paid a fat insurance. The fatal bottle and the insulin vile are found hidden in Amy s cabin. How will the Sloanes catch the killer?