As a luxurious ocean liner makes its way across the Atlantic Ocean, the audience is made privy to the travails of several of its passengers. Edmund Lowe heads the cast as Monty Greer, a suave gambler who falls in love with Judy (Lois Moran), the daughter of immigrant lens grinder Rudolph Kramer (Jean Hersholt). In trying to recover some valuable securities stolen from banker Henry Graham (John Halliday), Greer finds himself in the middle of a fierce gun battle in the ship's engine room. Meanwhile, Graham, who has been cheating on his wife Kay (Myrna Loy) with sexy dancer Sigrid Carline (Greta Nissen), is murdered by person or persons unknown. And that's only three of the plot strands in this marvelously complex shipboard thriller.