Death on a steamer

The Lusitania, one of the most luxurious transatlantic liners in the world, sails from New York on May 1, 1915, bound for Europe, where World War I had recently broken out.
At table no. 22 in first class, a diverse group of wealthy passengers gathered, including a wealthy industrialist, a former British vice-consul, and the wife of a Canadian officer. One day, a body is found in a locked cabin with the key inside, and the deadly weapon is not found. At the captain' s request, Patrick Gallagher, a civil servant of Her Majesty' s Government, takes on the investigation of the murder.
Day by day, the mystery of the locked room is getting closer, but so is the disaster of the sinking of the Lusitania, comparable in number of victims to the sinking of the Titanic three years earlier.