Appointment with Danger

Postal inspector Harry Gruber is killed by Joe Regas and George Soderquist at the Hotel Compton in Gary, Indiana. They dump the body in La Porte during a heavy rainstorm, and Sister Augustine passes nearby. She reports what she saw to the authorities, setting the case in motion.

Al Goddard is assigned to the case and begins organizing the investigation. He travels to Fort Wayne to locate Sister Augustine and gains her trust by quoting Martin Luther on personal responsibility. She agrees to go to the police station and to Gary later for testimony.

At the police station, Sister Augustine identifies Soderquist from a mug book. She then commits to staying at a convent in Gary until she is needed for testimony in court.

Soderquist is seen with Ferrar by Goddard and Augustine, but he manages to slip away. The hunt continues as the conspiracy remains active.

Regas, whom Augustine does not recognize, sees her and phones Earl Boettiger to warn him to hide Soderquist. The warning shows the gang's panic to protect their unstable member.

Soderquist refuses an order to leave town and is killed by the gang. His death is intended to quiet a problem, but it raises the risk of arousing suspicion.

Goddard realizes the gang may still be planning something since Soderquist remains in town. He speaks with the Gary postmaster, who points to a money shipment that changes trains and requires a seven-minute truck transfer.

The postmaster notes Ferrar as the driver who recently turned down a higher-paying job, linking him to the planned robbery. Goddard connects Ferrar to the gang's operations through prior encounters.

Goddard, posing as a corrupt inspector, pressures Ferrar to meet the gang's head and tries to recruit Boettiger as an inside man, hoping to steer the plan from within.

The gang outlines a plan to steal a money shipment worth about $1 million, coordinating the train-to-truck handoff. Boettiger is positioned to play a key inside role.

Boettiger's hotel mistress, Dodie, overhears the plot and protects herself by not becoming an accessory, while deciding to leave town to stay out of trouble. She indirectly informs Goddard about the plan.

The robbery does not go smoothly because Regas neglects his part. When the gang gathers, Sister Augustine blurts out Goddard's name, revealing that she knows of the deception.

Goddard pleads with the gang not to harm Augustine and starts a fight to delay them, buying time for the arriving authorities. The tension peaks as the police move in.

Police arrive and a fierce shootout erupts in the industrial district, leading to the deaths of all the gang members. The case closes with the imminent fate of the criminals and the safety of Augustine in the aftermath.