Jim and Artie ride to Hayes City and go to the mortuary, unaware that Deuce and two of his men are watching them. The agents go inside and ask for Sheriff Quail, who directs them into the next room. Dr. Miguelito Loveless is lying in state. The elderly Quail says that he shot Loveless when him and three men were robbing the local bank. Artie confirms that Loveless isn’t breathing and the agents remove their hats in respect.
A woman comes in and cries over Loveless’ corpse, and then grabs the key fastened to his wrist. She draws a gun on the agents and shoots Quail when he reaches for his flask. Jim disarms the woman, Triste, but Deuce and his men come in. Deuce demands the key and calls Triste by name, and Artie hands it over. Jim hands over Triste’s gun but uses it as a distraction to attack Deuce and his men. A fire breaks out and the men duck out the back while Triste goes out the front. The agents haul the wounded Quail to safety while the mortuary goes up in flames.
The next morning at the Wanderer
, Artie tries to work out what happened. He has the real key, and tells Jim that he gave Deuce a different one. A carrier pigeon arrives with word from the Bureau on the key. The serial number belongs to a safety deposit box in Mendoza taken under the name Gideon Blodgett. The agents take the train to Mendoza and speak with the manager, Welles. He informs them that two other people demanded to see the box and confirms by description that they were Deuce and Triste. The agents put the key in the box, but it explodes and they manage to get out of the vault just in time. There’s a small canister inside containing the key for a neighboring box. Artie opens it this time the sound effect of an explosion goes off. Inside the box is a single envelope and a noisemaker.
The letter from Loveless inside says that they should look up Arthur Tickle. Welles lets them out and the agents quickly depart. Artie rides off to find Triste, while a man comes out from the bank and tells Jim that he’s going past Tickle’s house.
At the Wanderer
, Triste sneaks in and searches the drawers, taking care not to wake the sleeping Artie on the couch. She finally sneaks up on him in the dark and hits him with a blackjack... only to discover that it’s a dummy. Artie emerges and quickly disarms her, and explains that he was expecting. He has supper and wine waiting and wants to discuss the key.
Jim rides out to the Tickle home with the man from the bank, who directs the agent down the proper road. When no one answers, Jim goes inside but doesn’t find anyone except for a talking myna bird. It talks in mimicry of Loveless’ voice, and congratulates Jim on outliving him. The bird then asks Jim to be the executor of his estate so that his next of kin will be protected. Loveless’ lawyer will fill in the details, and the bird takes a gold medallion out of its seed tray. Jim takes it and determines that it has a combination on it. The man from the bank comes in and Jim realizes that he’s Tickle. The lawyer admits that Loveless was eccentric and gave orders to get Jim there and train the bird, and that he would provide incriminating files in return for Jim’s assistance.
Jim asks about the combination and Tickle says that Loveless knew where Jim would find the locker. The lawyer then brings in Loveless’ next of kin, his uncle, Swiss neurologist Dr. Werner Otto Liebknicht. Liebknicht is similar to Loveless in height and appearance, and Tickle explains that he was working with his nephew to build a sanitarium. The doctor says that his nephew told him that Jim was a wicked person who prosecuted Loveless and has to die.
Deuce and his men ride up to the house and open fire. Jim returns fire, protecting Tickle and Liebknicht, and Deuce tells him to turn over the key. Liebknicht suggests that they hand it over, but Jim says that it’s the property of the government and that Deuce will kill them anyway.
As they finish dinner, Artie admits that Triste has resisted his charms. She figures Jim and Artie already know everything, but he wants to learn who she’s working for and what the prize is at the end of the trail. Artie warns her that her beauty won’t last once she’s behind bars, and describes what will happen to her in great detail. Triste finally cracks and explains that Deuce is trailing Jim to find Tickle. She offers to take Artie to Tickle in return for a break and Artie agrees.
Deuce suggests that they surrender and Tickle wants to accept his offer. Liebknicht agrees with Jim, who returns fire. One of Deuce’s men throws a phosgene gas grenade and the three men start to choke. Jim confirms that Tickle’s buggy is in the barn. Tickle panics and runs outside, and Deuce guns him down. Liebknicht agrees to follow Jim. They crawl below the gas and Jim takes the myna bird with him. The two men go out the window and head for the barn, and Deuce and his men move in. Jim blasts the door off of the barn and rides out, and the bad guys ride after them. Once they’re briefly out of site, Jim and Liebknicht get out of the buggy and whip the horses, sending them on ahead. Deuce falls for the ruse and follows the buggy, but Jim warns that Deuce won’t be fooled long. The agent suggests that they go the sanitarium to look for the files that Loveless promised.
Artie and Triste arrive at Tickle’s house and find the lawyer’s corpse. They hear the myna bird behind the house and Artie goes to investigate it. Triste grabs his gun, shoots the agent, and rides off. A Secret Service agent, Hayden, runs out and confirms that Artie is okay and set up the whole thing. The myna bird is making seagull noise and Artie figures that it was trained somewhere near the coast. They then take off after Triste.
Liebknicht leads Jim to the sanitarium and an abandoned mine tunnel that runs beneath it. Deuce and his men come in and open fire. Jim and Liebknicht run further into the mine and Jim uses a hidden explosive to seal off the tunnel behind them. They get to the entrance and Jim uses a second charge to bring down the roof and trap the men in-between. Liebknicht leads Jim to a hidden elevator upholstered in style. As they ascend to the sanitarium, Liebknicht again accuses Jim of prosecuting his nephew, but agrees to let bygones be bygones.
The two men arrive in Loveless’ office, covered with mobiles of Earth globes. Jim asks Liebknicht for the files now that he has fulfilled his obligation to protect the neurologist. Liebknicht honors his nephew’s wishes and reveals the safe. Jim uses the combination to open it and confirms that the files reveal Loveless’ foolproof plan to capture the U.S. Mint. Triste comes in and Liebknicht removes his disguise to reveal that he’s Loveless. Loveless explains that he used the art of yoga to temporarily enter a lifeless state. When Jim wonders what the reason was for the ruse, Loveless explains that Deuce was becoming troublesome and he needed Jim to eliminate him. Jim falters and Loveless tells him that a hidden gas nozzles has been releasing anesthetic gas ever since he opened the safe. After a moment, Jim collapses.
Two doctors arrive at the sanitarium and are escorted further into the complex. Artie arrives next and knocks out the guard with a gas-filled balloon. When the other guard returns, Artie tries to bluff his way through, claiming to be the last doctor to have arrived. When that doesn’t work and the guard checks his list, Artie claims that the man has a neurological condition. The nervous guard admits that he isn’t taking any treatment and Artie checks his temperature with a drugged thermometer. Once the guard passes out, Artie confirms the name of the last doctor from the list, Dr. Ramone LaPoliche.
Orderlies put Jim on a gurney and take him through the hallways of the sanitarium to an operating theater. The visiting doctors (including the disguised Artie) have assembled to watch Loveless, who claims Jim is a deluded patient who believes that he’s a Secret Service agent. Loveless plans to destroy the frontal nerves, transforming the patient’s personality. Artie interrupts to ask for all of Jim’s vital signs. As he checks Jim, he slips him a knife and Jim cuts himself free. The two agents take out the orderlies while Loveless escapes into the hallway. Jim and Artie get out and lock the door, and Artie uses an explosive to bring down the wall.
The agents decide to release the screaming inmates as a diversion, only to discover a series of record players. They continue to Loveless’ office and find the doctor and Triste waiting for them. Jim gets the files while Loveless complains that it took all of his efforts to get the visiting doctors out of the sanitarium. Loveless then tells Triste that he’ll be back for her and his chair drops back through a hidden panel. The files explode and Artie realize that the entire room is treated to spontaneous combust. Triste refuses to help them escape via the elevator until the agents point out that she’ll die with them. The woman throws the hidden switch and they escape into the mines. Outside, they watch as the sanitarium burns to the ground. Triste cries, assuming that Loveless died, but Jim and Artie don’t believe it.
Later, Jim and Artie bring their dates back to the Wanderer
and find a package waiting for them. They open it and find a carved wooden box with a key. When Jim inserts the key into the box, another one of Loveless’ noisemakers goes off and they realize that their nemesis is still alive.