November 1924. The glitzy and glamorous Endeavour sails from England to New York with 2,000 passengers - and a killer - on board. When an elderly gentleman is found dead at the foot of a staircase, ship’s officer Timothy Birch is ready to declare it a tragic accident. But James Temple, a strong-minded inspector, is certain there is more to this misfortune than meets the eye. Birch agrees to investigate, and they form an uneasy partnership. Uncovering a web of surprising connections between the passengers aboard the Endeavor, running from the crew cabins below deck to the palatial suites of first class, their inquiries lead to the theft of a priceless painting. Its very existence is known only to its owner . . . and the dead man. With just days remaining until they reach New York, the search for the culprit is fraught with danger. And all the while, the passengers continue to roam the ship with a killer in their midst. One who is poised to strike again.