When Lt. John Harkness is assigned as the new skipper of a submarine chaser equipped with an experimental steam engine, he hopes that the U.S.S. Teakettle's veterans will afford him enough help to accomplish the ship's goals. Unfortunately, he finds the crew and its officers share his novice status or only have experience in diesel engines.

After being found wandering the streets of Los Angeles, a severely catatonic woman tells a doctor the complex story of how she wound up there.

A teacher writing a book about gambling meets a hotel/casino owner threatened by a gangster.

Kirby Frye, a former Confederate officer but now a Union Cavalry scout, is sent into Montana territory to locate and retrieve three Gatling Guns stolen from the U.S. Arsenal by outlaws believed to have taken them west to sell to the Soiux and Cheyenne. The trail leads him to Red Bluff where, aided by Claire Corville, he and the audience discover together and real quick like that Martin Gavin, a supposedly-honest operator of a freight line, has the guns and intends to exchange them to the Indians for furs.

An ex-gunfighter woos two women while avenging his brother, victim of a crooked gambler.

Roy Martin aka Roy Morgan is a burglar and former war-time Radio & Electronics Engineer who listens in to radio police calls, allowing him to stay one step ahead of the cops.

Quiet, organised Dr. Talbot meets nightclub singer Nora Prentiss when she is slightly hurt in a street accident. Despite her misgivings, they become heavily involved, and Talbot finds himself faced with the choice of leaving Nora or divorcing his wife. When a patient expires in his office, a third option seems to present itself.

When they learn that their brother Matt Denton is awaiting trial in California, charged with train robbery, deputies Tom Denton and Fred Denton leave their home in Fort Grant, Texas and head west. They arrive in Tulare just in time to rescue Matt from being hanged, but a guard is killed during their escape. Ed Larkin who framed Matt, falsely accuses them of a long list of crimes. They return to Fort Grant so that Tom can see his sweetheart Laura Brook. They encounter outlaw Bill Devlin who persuades them to hold up a train which Laura unwittingly told them would carry a large payroll. Soon the whole territory is enraged at their deeds. They return to Fort Grant to hold up the two banks that are filled with huge sums of cattle money.

The secretary of an affably suave radio mystery host mysteriously commits suicide after his wealthy young niece disappears.

As novice detectives, Bud and Lou come face to face with the Invisible Man.