This book always heads my list of best mysteries/detective stories. Peter Lovesey is witty and had a wonderful way with words that makes his books page turners. His characters, plots, situations, and twists are always interesting. And on top of those superlatives, imo this is his best book.
Most of the action takes place upon the luxury liner Mauritania. The book gives a true feeling for the period and shipboard setting. A few historical characters are mentioned or have small roles and all of them are handled truthfully and believably. The detective in the story qualifies as one of the most unlikely in the all of detective fiction.