Mark is asked by a friend to cover for a cruise ship's Doctor, who has gone on his honeymoon, splitting the medical duties with Jesse and Amanda, and Steve tags along for a much needed vacation. Barely aboard, they must save multimillionaire Robert Brantigan, who somehow had taken a triple dose of insulin. Jesse and Amanda drown in patients, especially after Mark takes on the duties of the injured Activities Director. Robert goes missing, and his wife Clare reports him missing to the ships' Captain. News reaches the cruise ship that his drowned body has been recovered. Steve learns Robert's daughter Tracy (from his first marriage) has access through her pharmaceutical internet business to the drugs that are found in Robert's body during Amanda's autopsy, and she determines he's been murdered. His wife suggests he may have been suicidal, and definitely drunk when she saw him the night before, then accuses his daughter Amy, who confides in Steve that his recent angry outbursts were due to a brain tumor he'd told nobody else about. The L.A.P.D. talks to the sister of Clare's first husband, Carl Donahue (who also perished at sea on a cruise), but Clare points out she wasn't then, and isn't now in her husbands' will - but the sister tells Steve she was paid handsomely by his insurance company. Key pieces of evidence are found hidden in Amy's cabin. Will Mark, Amanda, Steve and Jesse be able to put all the clues together to catch the killer?
—KGF Vissers/edited by canadazbest