Legion of Terror

Frank Marshall and Slim Hewitt are sworn in as postal inspectors in Washington, D.C. They face a clue linking to Stanfield, Connecticut when a suspicious mail bomb surfaces. The assignment marks the start of their undercover investigation.

A bomb addressed to a U.S. Senator is found in the Senate mailroom. Frank and Slim are dispatched to Stanfield to trace the connection and root out danger in the town. The assignment pulls them into a sinister political-underground plot.

During the train ride to Stanfield, Frank becomes acquainted with Nancy Foster, a resident of the town. The journey sets up personal stakes for the mission and introduces a potential ally and love interest. Their connection foreshadows the conflicts to come.

Frank and Slim arrive in Stanfield and assume new identities to blend in. They secure jobs at a local factory to observe the Legion's influence and gather evidence. Don, Nancy's brother, begins to reveal the danger gripping the town.

Frank attends dinner at Nancy's house where Don warns him about the Hood Legion's total control. The revelation confirms the scale of corruption in Stanfield and raises the stakes for Frank's undercover work. The dinner scene exposes the intimate costs of the mission.

Don receives threatening letters urging him to join the Legion. Frank and Slim infiltrate the group by undergoing an initiation ceremony, during which masked members blindfold them and brandish guns, finally giving them a bullet as a token. The rite secures their cover and grants access to the inner circle.

Don reports the Legion's activities, but McCollum frames him for drunk driving and he is arrested and ostracized. The Legion conducts a secret tribunal in the woods, where Don is tried and shot by its members. The brutality reveals the extent of the town's corruption.

Nancy tries to report the killings to the authorities, but law enforcement cannot locate the killers. When Frank comforts her, she forces him to confess his Legion membership and swears not to speak to him again. The secretive, personal cost of the undercover operation becomes clear.

Nancy takes her story to the local newspaper owner, who publicly upbraids McCollum for his complicity. In retaliation, McCollum orders Nancy to be tried by the Legion's tribunal. Slim confronts McCollum with evidence of Don's murder and is escorted toward the Legion's meeting ground for a traitor's hearing.

Frank learns Nancy and Slim are being held prisoner and travels to the governor to secure the National Guard. A coordinated rescue frees Nancy and Slim and results in the arrest of Legion members. The raid marks a decisive shift in Stanfield's fight against the Legion.

It is revealed that McCollum was the Hood Legion's leader. He and his assistant attempt to escape, but their car overturns and catches fire, killing them. The collapse of leadership exposes the true danger of the organization and its hold over the town.

Frank reveals his true identity to Nancy as their relationship survives the ordeal. They plan to marry, signaling a personal victory amid the political battle. The couple's bond endures despite the surrounding danger.

Back in Washington, the Post Office chief inspector congratulates Frank and Slim for their work. He warns that Americans are 'joiners' and can be drawn into dangerous organizations, underscoring a moral about vigilance against racketeers.