Five years ago, a police agent, Martin Schwarz, had his wife and son—who were traveling on the cruise liner “Sultan of the Seas”—go missing. At the time, the cruise company insisted it was suicide. But Martin didn’t believe it. Then a passenger from that same liner calls him and says he must immediately come aboard the “Sultan of the Seas.” She claims she has evidence that his wife did not throw herself into the sea of her own will. What’s more, perhaps his son is still alive, and strange things are happening aboard the ship. Dropping everything, Martin goes on an unwanted journey, determined to dig out the truth…