The friendship of two working stiff railroad engineers is put to the test when one falls for the other’s wife.

A pretty Chinese woman, seeking help from San Francisco detective James Lee Wong, is killed by a poisoned dart in his front hall, having time only to scrawl "Captain J" on a sheet of paper. She proves to be Princess Lin Hwa, on a secret military mission for Chinese forces fighting the Japanese invasion. Mr. Wong finds two captains with the intial J in the case, neither being quite what he seems; there's fog on the waterfront and someone still has that poison-dart gun...

Construction workers in World War II in the Pacific are needed to build military sites, but the work is dangerous and they doubt the ability of the Navy to protect them. After a series of attacks by the Japanese, something new is tried, Construction Battalions (CBs=Seabees). The new CBs have to both build and be ready to fight.

John Breen (John Wayne), a Kentucky militiaman falls in love with French exile Fleurette De Marchand (Vera Ralston). He discovers a plot to steal the land that Fleurette's exiles plan to settle on and aims to foil it.

Captain Ralls fights Dutch shipping magnate Mayrant Sidneye for the woman he loves, Angelique Desaix, and for a fortune in gold aboard the Red Witch.