Detective Speed goes to hear a speech from Senator Snazzle. After a rousing diatribe against the Nazis, Senator Snazzle is alone in a room with a man named Smith. When Smith is shot dead, Trigger Quick burst into the room to investigate. Snazzle claims he was attacked. Inspector Smooch, a sergeant, discovers the murder weapon in Trigger's pocket. He arrests Trigger as the prime suspect.
Sitting with Rang-a-Tang and Richy the Amazing Boy the following morning, Hy reads that Trigger is in jail. They go to get Trigger released, afterward going to the senator's home. They senator introduces his wife, Mrs. Snazzle. Detective Speed tells them that Trigger will stay at the home as a bodyguard. Upon leaving, Hy leaves Richy with Rang-a-Tang, admonishing them to watch the house without letting anyone know, including Trigger.
Later that night, Trigger helps himself to a snifter of brandy, but discovers it's been drugged. The cocktail knocks Trigger out. A dark figure sneaks in through a window and strangles Mrs. Snazzle. The figure leaves the house, yet is followed by Rang and Richy. They observe the senator go to a warehouse and report to a group of Bundonians working for the Nazis. Richy climbs up the building to help him hear the conversation better, but a rain spout gives away at the strain and alerts the Bund members inside. Richy has to fight his way out, but is overcome.
Detective Speed investigates the Smith murder scene when Rang-a-Tang rushes into the room. Hy takes Rang with him and rushes to the Snazzle home. He discovers Trigger passed out from the drug and the body of Mrs. Snazzle. When Senator Snazzle walks in, Hy interrogates him, but Rang attacks the senator. Snazzle kicks the German shepherd and knocks Rang out cold. He pulls a gun and admits his guilt to Hy. Trigger wakes up, confused when Speed tries to warn him. The detective tackles Snazzle and wrests the gun away.
Snazzle reveals that the Bunds are holding Richy. Rang recovers as the police arrive. The canine leads them to the hideout of the enemy provocateurs. There is a gun battle between the lawmen and the Bundsmen. Rang climbs onto the roof and bursts into the room through a skylight. Hy bursts in with the police to rescue Richy and arrest the spies. Trigger Quick says he intended to give Snazzle enough rope to hang.