An outbreak of cholera threatens a luxury liner in this surprisingly low-budget melodrama from RKO. En route from Shanghai to San Francisco, chief engineer Crusher McKay (Victor McLaglen) and shipboard doctor Tony Craig (Chester Morris) become rivals for the attention of nurse Ann Grayson (Wendy Barrie). A Chinese stowaway, meanwhile, infects the stokehold with cholera and it is left to Crusher to keep the engines at full throttle until reaching harbor. But morale sinks to an all-time low when Crusher himself is stricken and the overworked men threaten with mutiny. Tony attempts to keep the stokers in check but the situation is growing more dangerous by the minute when a heroic Crusher rises from his sickbed. Leaving their previous petty squabbles behind, Tony and Crusher manage to guide the ship safely to harbor, where the doc and Ann rekindle their romance.

Su un piroscafo in navigazione sul Pacifico scoppia un'epidemia di colera. Il capo macchinista, irascibile e severo coi sottoposti ma in fondo di buon cuore, si prodiga per la salvezza dell'equipaggio anche a costo della propria incolumità.