Police officers arrive at the hospital where an elderly female witness, Gladys Collins, has just come out of a coma. Before they arrive, a Mob killer named Arthur posing as a doctor enters Gladys’s room and secretly plans an explosive charge on an oxygen tank. The man slips out just as the police arrive. The detective in charge, David St. James, talks to the barely-conscious Gladys and asks for help to put away gangsters Tommy Kroll and Frank Stevens. As she starts to talk, the bomb goes off, killing them all.
Jim picks up his tape briefing at an empty fire station. He’s informed that Stevens and Kroll run a criminal empire and plan to take over the entire northeastern U.S. There is not enough evidence to convict them, so the IMF must put the two men out of business for good.
At the team meeting, Jim shows the team a photo of Crowley Square and explains that hidden somewhere there is the body of Danny Ryan and the guns that Stevens and Kroll used to kill him. The plan is to recreate Crowley Square like it looked in 1937 on the day that Kroll and Stevens killed Danny, and they have to keep Kroll contained within the studio set that they’re using. They have rerouted all air flights over the area for six hours. Gladys remained silent out of fear since the two gangsters have eliminated anyone that could pose a threat to them. New IMF agent Casey has talked to Kroll’s old housekeeper and confirmed exactly what his apartment looked like. Agent Bill Fisher will be impersonating Stevens in 1937 with Casey’s help on the mask. They don’t have any old photos of Gladys Collins, but Kroll only saw her on the day of the murder and Casey has used computer reconstruction to approximate it. Barney has everything set up at the barber shop that Kroll frequents. Jim warns the team that Kroll is violent and unstable and will be dangerous every step of the way.
Kroll limps into the barbershop and finds Willy there. Willy says that he’s the owner’s nephew and the owner, Paul, is out with the flu. The IMF agent assures him that he knows his schedule and what he wants. As Willy seats him and applies a hot towel, the rest of the team watches through a one-way mirror. The towel has knockout gas on it, and once Kroll is partially unconscious, Barney throws several switches causing the walls to swivel around. The new walls are decorated in a 1930s style and a dazed Kroll sees the new décor. Barney then changes over the recording of a baseball game to one from 1937. Fisher then comes in posing as a gangster, says he has a message from Danny Ryan, and “shoots” Kroll as Willy hits the gangster with a knockout needle.
The team goes to work and Jim searches Kroll’s jacket. He’s looking for a particular watch but doesn’t find it. The dossier says Kroll always has the watch, which stopped the bullet that saved his life in 1937. Jim goes to Kroll’s apartment to find it while the others load Kroll into a van and drive him to the studio lot. Dozens of movie crew members are making up the area to look like Crowley Square in 1937.
Jim breaks into Kroll’s apartment, unaware that the gangster’s mistress, Carol Swanson, is in the bedroom. She watches as Jim searches the apartment and then hides in the bathroom as she checks the bedroom.
Casey makes Fisher up to look like a young Frank Stevens. Doug, Barney, and Willey give Kroll a trim, dye his gray hair black, and inject paraffin that will temporarily remove his wrinkles.
Jim finally finds a repair receipt in Kroll’s jacket and calls the team to tell them that they’ll have to keep Kroll out for another 45 minutes. Doug warns the team that they’ll lose time on the other end and that the temporary injections will wear off in six hours. Meanwhile, Carol waits until Jim leaves and then calls Frank Stevens to tell him what happened.
At the jewelry store, Jim presents the receipt to the proprietor and claims he’s working for Kroll. He intimidates the owner into handing over the watch and the man comments on the dent in the casing.
Stevens and Arthur go to Kroll’s apartment and Carol tells him what she overheard. They figure that Jim was a cop and Stevens tells his men to check out the barber shop and the jewelry store while he has the phone traced. Carol asks about Kroll and Stevens, unimpressed, tells her that he’ll tell Kroll that she was concerned. He then calls the phone company to run the trace.
Barney replaces the contents of Kroll’s wallets while Doug gives the gangster a painkiller to clear up his limp. Jim arrives with the watch and puts it in Kroll’s jacket pocket.
Kroll’s man goes to the barber shop and discovers that it’s closed.
The team takes Kroll to their fake barbershop from 1937. Jim shoots out the mirror and they set up Willy as a corpse. Doug then wakes up Kroll and everyone leaves. Kroll wakes up and is shocked to discover that he’s thirty years younger, wearing the same clothes that he was in 1937 when he was shot on June 30. There’s a hole in his jacket where a bullet hit the pocket watch. The newspapers and magazines are properly dated and the radio is still announcing a baseball game of the period.
As Kroll examines himself in the mirror, pedestrians run up at the sound of the shooting. Jim and Barney, posing as policemen, arrive at the barber shop. Jim demands that Kroll tell him who did it, figuring it was one of Ryan’s boys. Fisher comes in, disguised as Stevens, comes in to check on his partner. Kroll tells them all to get away from him and runs out into the street. Everything is an exact replica of New York City in 1937. Jim and Barney put him under arrest and take him to the station.
Arthur talks to the jewelry store proprietor, who insists that Jim had the receipt. He gets a description of Jim.
Jim interrogates Kroll, reminding him that he and Ryan fell out over territory a week ago. They describe the fight where Kroll, Stevens, and Ryan met, and a dozed Kroll tells them to leave him alone. Barney plays the good cop, saying that Kroll must have been hurt, but Jim pressures him into talking. When Kroll doesn’t say anything, Jim has Barney lock the gangster up. As Barney takes him to a cell, he checks Kroll’s memories and pushes home that it’s June 30, 1937. He then puts Kroll in a cell with a drunk and leaves.
Willy and Casey set up the fake set of Kroll’s apartment, complete with fake bills and a radio filled with tape players.
Kroll asks the drunk how old he looks, who insists that he appears to be in his 30s. The drunk confirms that it’s June 30 and Kroll grabs him. The extra inadvertently drops a 1964 half-dollar piece and manages to cover it up without the gangster noticing. Barney and Jim arrive to tell Kroll that Stevens has posted bail and take him away.
Arthur reports back to his boss, who figures that Jim isn’t a police officer.
Fisher walks with Kroll and says that they need to figure out what to do about Ryan. Kroll is more interested in figuring out who Jim is, since he’s never seen him before. Fisher dismisses his concerns and takes Kroll to his (fake) apartment. The apartment is a replica of Kroll’s and he examines the bill that the IMF planted. Fisher insists that they need to hit Ryan, but Kroll is busy trying to figure out if what he’s seeing is real. He turns on the cabinet radio and gets (pre-recorded) 1937 radio broadcasts. Fisher suggests that he call Gladys, his old girlfriend, who is with Ryan now. Kroll tells him that Gladys is dead and he had him Arthur kill her a week ago. He then starts falling apart, figuring that his whole lifetime since 1937 has been a dream. Fisher says that Gladys isn’t dead and tells Kroll to pull himself together before he gets them both killed. While he goes to call Gladys, Kroll takes his revolver from out of the radio cabinet.
Stevens’ contact at the phone company calls and tells him that he’s traced the call to a movie studio.
Casey, posing as Gladys, arrives at Kroll’s apartment. Fisher explains that Ryan took a shot at Kroll, but claims that they want to work out a deal with their rival. He asks Casey to set them up for a meeting at a café that night at 6 p.m. She realizes that they plan to kill him and refuses to help, while Kroll hears a plane pass overhead. He goes to the window and sees that the plane is a 1937 propeller plane, provided by the IMF. Kroll finally accepts the reality of the situation and tells Casey to set up Ryan or he’ll kill her. The IMF, listening in, head back to the fake Crowley Square.
Arthur drives to the studio lot and asks about Kroll. The guard claims that Kroll isn’t there and doesn’t know anyone matching Jim’s description, and the killer draws a gun on him. He forces the guard to take him to Doug, but Jim knocks him out. Realizing who Arthur is, they have security lock the gates.
Casey calls Ryan and asks him to meet her at the café to discuss her new out-of-town job. Once she’s done, Fisher insists that they’ll make peace with him. Kroll calls his mother to assure her that he’s okay, and Jim provides a busy signal. He then suggests that Fisher take a walk, but Fisher points out that he’s been acting strange all day and he won’t leave him alone. Kroll agrees to stay with him but insists that they go to a movie.
Willy and Barney drive to the real-life café, which is now abandoned, and break into the building.
Kroll insists on going in with Casey to the movie, and they settle in to watch a 1937 film.
Doug makes himself up as Ryan in 1937.
When he doesn’t hear back from Arthur, Stevens calls three men in to go check on Kroll.
At the theater, Kroll defends himself to Casey and takes his hand. He tells her that she’d like him if he gave her a choice, but Casey says that she’ll think about it if there’s no killing that night.
Jim gives Fisher a tie clip with a mike and tells him that they have to move things along. He then gives the disguised Doug a blood capsule.
Fisher enters the theater and tells Kroll that everything is ready and there’s a getaway car behind the café. The three of them go to the café movie set and tell the owner to close up the joint, and then sit down to wait. Outside, the disguised Doug pulls up and goes inside. Kroll has second thoughts, but Fisher says that it’s too late. Doug comes in and Kroll and Fisher shoot him down. Casey runs out as the two men haul the body out to the car. However, when sirens go off in the distance, the getaway car drives away. Fisher wonders what to do and Kroll, remembering what he did 30 years ago, takes Ryan’s body to the cellar.
Barney and Willy, listening in, go to the cellar and get ready to search.
Kroll and Fisher take the body to the fake cellar and Kroll says that they can put the body in the hidden room where the owner kept booze during Prohibition. Willy breaks down the fake wall in the real cellar and they find Ryan’s corpse inside, along with the murder weapons.
A desperate Kroll tries to find the hidden door on the fake set without success. He turns around and discovers that Fisher and Doug have slipped away. As the team drives off, Kroll realizes that Fisher and the corpse are gone and runs outside. The streets are deserted and Kroll runs down the streets as the drugs and the treatments wear off. Limping, he leaves the movie set and finds himself in a neighboring one containing an Old West town. Stevens and his thugs break into the studio and find a confused Kroll standing in the middle of the street.