Though this does go a bit off course from time time, a boat - like a train - does provide for quite a good stage for an engaging mystery peppered with loads of melodrama. "Greer" (Edmund Lowe) is the suave and debonaire gent who hopes to make an easy living on the cards and on the roulette wheels abroad this liner. He quickly becomes aware of a cunning wheeze by a gang of crooks to relieve wealthy tycoon "Graham" (John Halliday) of some of his wealth but declines to get involved. "Halliday" is not so happily married to "Kay" (Myrna Loy) and so keeps mistress "Sigrid" (Greta Nissen) in the styl...