Baxter and his men are in a race against time when a derelict steals a jar containing a highly combustible chemical that will burst into flame upon contact with air or water.
After being tipped off that a passenger on a liner docking that day will be shot, Baxter and his plain-clothes men stake out the pier and try to spot the would-be killer in time.
A well-known gangster and his men pressure watchmen at waterfront warehouses into keeping quiet while they loot various goods being stored there, by threatening them and their families.
Three hoods who frequent Ma Sperling's Harbor Mission have been robbing local businesses. When one of them muffs a job the other 2 rub him out. When Ma finds some gems they stole, she may get rubbed out too.
A porter on a passenger liner kills a jewel smuggler in his cabin, then tries selling the gems in San Francisco pawn shops, until the smuggler's partner catches up with him.
Embezzler completes his 5-year sentence and immediately returns to his former employer seeking revenge. After killing the man whose testimony put him away, he must flee from the Harbor Command.
A criminally insane sailor vows revenge on the ship captain who fired him. The madman has the technical skill to make good his threat, and rigs up a nitro-charged boat bomb while Captain Baxter scours the waterfront to prevent disaster.