Thieves steal an army tank and use it to start robbing banks along the Mexican border.

Hank and Johnny are assigned to investigate a series of raids against Mexican towns along the border. They come to suspect that German troops who are disguising themselves as American soldiers are committing these attacks in order to instigate a war between the US and Mexico.

A Mexican revolutionary is in the US raising funds for his efforts to overthrow the Mexican government. The Mexican army sends an officer to the US to kill him.

Hank and Johnny travel to a small town that has been taken over by a band of would-be revolutionaries.

Ex-convict Joe Bascom kidnaps a priest from the town that hanged his father, and demands that the citizens there hang one of their own in return for the priest's life.

A female newspaper reporter hires Johnny and Hank to rescue a priest and a group of Indians who are being held hostage at an archaeological dig by thieves who are looking for buried treasure.

Johnny and Hank come into a town that is having problems with its oil wells being sabotaged, and the residents are blaming Indians from a nearby village for the damage. The two try to find out who's behind the sabotage before the angry townspeople attack the village and start an Indian war.

A prison in Texas is taken over by a German military intelligence officer, who believes that the inmates would provide a fertile ground for recruiting saboteurs. Hank and Johnny have to come up with a plan to break into the prison and stop the German.

Johnny and Hank butt heads with a ruthless rancher while searching for a friend's son, who vanished while engaged in a secret mission for the army.

Hank puts himself out as bait to catch a mercenary saboteur who is destroying medical supplies being shipped to the Allies in Europe.

A renegade army colonel steals some heavy artillery in order to destroy a convoy of explosives headed for England.

Hank and Johnny call on their old friend Raoul Esteban to help prevent a gang from destroying a mining town.

Hank and a candidate for governor are kidnapped, and Johnny is forced to rely on an ex-convict to help find them.