John Dortmunder (Robert Redford), an inmate, goes through the exit process at a prison, including retrieving his old clothes, verifying his identity with a finger print, and retrieving his belongings. The warden offers him his rehabilitation speech but John says hes been successfully rehabilitated by the warden's program. The warden sarcastically implies, whatever prison he will wind up working for, that he will see John again.As John walks away from the prison, a car follows him, with the driver calling his name. John runs. When the driver finally catches up to him, he identifies himself as his old pal. John punches him.They drive into the city. The driver, Andrew Kelp (George Segal), hands John a beer and it turns out Kelp is married to John's sister. Kelp asks how his time was and John interrupts saying he's not going to work a job with him. Kelp, feigning offense, starts to tell John about a job.They are at a museum, with a crowd, studying a 10 by 5 by 5 display case holding The Sahara Stone. John doesn't think it's do-able. Kelp recommends John meet The Doctor, the money man, before he makes a decision. Kelp tells John not to mention that he has been in prison so as not to undermine The Doctor's confidence.They meet The Doctor (Moses Gunn) at a park. The Doctor explains that he wants the Stone so that he may return it to his native country which has been fighting with a neighboring country over the ownership of the diamond for generations. The United Nations is deciding the Stone's fate, but The Doctor would be more comfortable if his nation was in possession of it should the UN make a bad decision.The Doctor says it's a four-man job and is offering a payment of $25,000 per man. Kelp and John negotiate with The Doctor to cover expenses during their planning process. The Doctor refuses; John leaves. Kelp tells The Doctor that John is just out of prison and has no means of support. The Doctor gives in. John comes back and The Doctor offers him $75 a week. John leaves again. Kelp says he can convince John to do it if he is offered $150. The Doctor agrees.Kelp catches up to John and John lists the arguments against doing the job: that The Doctor is not experienced in a job; that the position of the stone within the museum (30 steps from the nearest exit); that the case is shatter- and bullet-proof, made with glass embedded with metal; and that there is no alarm system meaning the guards will be extra vigilant. However, John thinks the guards can be occupied with a well-planned diversion, and the locks seem easy to pick. He agrees to do the job.They stop by Kelp's locksmith shop and then go to his apartment. John's sister greets him warmly. John says he doesn't want to work with Kelp because if they get caught, no one will be around to look after her.A woman pulls up to a garage where her son, Stan Murch (Ron Leibman), proudly announces he's purchased a soundtrack album of the Daytona 500. He plays it for her to cheer her. They listen happily. The garage phone rings. It's Kelp.John goes to a bar and the bartender directs him to the back room. Stan is there and immediately goes into a description of the route he took to get to the bar, which explains why he got there early. Alan Greenberg (Paul Sand) arrives. Kelp arrives.Stan asks why they don't just keep collecting the $150 per week. John says there is a time limit on The Doctor's patience. Greenberg wonders why they just don't keep the Stone for themselves and negotiate with the insurance company. Kelp says The Doctor knows who he and John are, and he would rather not have the wrath of an entire African nation upon them. John notes that their prep work will involve a lot of pre-surveillance at night, and the neighborhood around the museum has been hit by muggings.At night, John cases the museum. There are a handful of guards milling around. Kelp works on some locksets at home.Kelp visits The Doctor at his office and presents him with a shopping list of the team's suit sizes for uniforms. The Doctor realizes that they are making progress and proudly identifies himself as a criminal.John and Greenberg are fishing by a quiet lake when John gives him a signal and Greenberg gets up and tosses a handmade grenade into the bushes. It explodes with a fireball. Greenberg tosses another that he learned how to make while studying at the Sorbonne and John says it has to be bigger. Greenberg reaches into his sack for another that he learned how to make while studying at Berkeley and John wants it bigger still, and noisier.At night, after closing, Kelp is casing the museum when a hippie hits him with a baton. Kelp yells for help and a museum guard comes out. As the guard holds a gun on the hippie, Kelp points a gun at the guard. With the guard blindfolded, they go inside. The hippie is John in disguise.Stan, down the block in a beater, checks his watch and then drives erratically toward the museum. He flips the car right at the main entrance and stumbles out as the car explodes. The guards come running out. Stan, lying on the ground with blood all over, repeats that he lost control of the steering.Kelp and John, dressed in guard uniforms, enter the display room. Kelp lies down next to the case and takes out a pick set. John is the look-out. Kelp takes a long time using various picks and John asks how it's going. Kelp almost falls apart, saying that John is only asking him because he has no confidence in Kelp. John reminds Kelp that if he is caught tonight, that he will go to prison for life; and that the reason he chose to do the job with Kelp is that Kelp has golden hands. Kelp gets back to work more confidently.It does not look good for Stan as the guards gather around. Greenberg pushes through saying he is a doctor. He enlists the guards to help him put Stan in traction because his ribs are scratching against his heart.Kelp is as surprised as John when the lock pops. He goes to work on the other lock. The guards all have their hands on Stan, holding him in position, and he cries out if they move the slightest. Greenberg runs off into the museum and changes into a guard uniform. Kelp has popped the remaining lock and the three of them try to lift the display case. They struggle but get it high enough for Kelp to sneak under and in to get the Stone. Greenberg loses his grip and they drop the case, trapping Kelp inside.The ambulance has arrived and takes Stan away. The guards head back inside. Kelp crawls out just as the guards enter. A chase ensues. Kelp and John escape. Greenberg is trapped and swallows the Stone.The next day, at Kelp's apartment, Kelp runs in proudly pointing at the front page of the newspaper. Stan is there, having escaped by assaulting a doctor in the ambulance. John asks Kelp if the article mentions the status of the Stone. Kelp assumes that Greenberg dropped it somewhere in the museum. Kelp asks what he should tell The Doctor. John says he doesn't care and leaves.John is at the doctor worried about ulcers, but the doctor tells him it is gastritis. He recommends John stay away from tense or argumentative situations. He thinks John internalizes his stress.Kelp has found John, with another job in mind, this time to break Greenberg out of state prison because Greenberg has the Stone. Kelp and John go to a quiet park and meet with The Doctor and Greenberg's lawyer (Zero Mostel). The lawyer tells them Greenberg will be happy to give them the Stone if they get him out of prison. Otherwise, Greenberg will exchange the Stone for a lighter sentence. It turns out the lawyer is Greenberg's father and he is not happy the others have corrupted his son. The lawyer gives John some notes and the layout of the prison.The lawyer visits Greenberg in prison and their conversation is a thinly veiled discussion about the plans for his escape.Kelp meets with The Doctor outside the UN and asks for a huge truck. Later, at night, a big rig pulls up outside the prison and Stan lets off Kelp and John. Kelp snips at a cyclone fence with bolt cutters and they enter the grounds, avoiding the searchlights. They cut through another fence and make it to the wall where they throw up a grappling hook and climb over. John pops an antacid and Kelp asks for one, thinking its hard candy. When Kelp realizes what it is, he's disappointed that for all these years he has envied Johns nerves of steel.Kelp picks a door lock to get them into the cell block. Greenberg gets out of bed and picks a fight with his cellmate; they fight. Kelp and John sneak through the kitchen. Stan opens the back door/ramp of the big rig. Two guards walk Greenberg into the prison hospital and Kelp and John sneak up behind them and drag off the guards. They run out of the building and back to the wall. Greenberg says he cannot climb the rope. Stan drives a convertible Mercedes out of the big rig. Greenberg struggles but makes it over. The spotlight catches John just as he is going over. The klaxon sounds and the guards start shooting, but the trio makes it through both cyclone fences and into Stan's car. He speeds off, erratically, and guns it full speed onto the ramp and into the back of the big rig. The door closes behind them. Greenberg urges them to drive off but Kelp says the plan is to wait until 6 AM and drive off with the other trucks, then they will exchange the Stone in the city. Greenberg confesses that he passed the Stone while he was in detention and hid it in the police station. The Doctor wonders why Greenberg didn't just keep swallowing it.John is outside the police station, casing the building. Kelp gives The Doctor another shopping order. Later, the team goes to a riverside location and get into a helicopter. Stan assures them he knows how to fly one. He flies them to the police station and they jump out - it's the wrong building. They make it to the correct building, set up equipment to jam the radio, and cut the phone lines. They throw smoke and tear gas bombs onto the street and the policemen rush out of the building. The Stone is not where Greenberg left it.Back in the helicopter, Stan declares he's had it with the Stone. John thinks he's been personally jinxed by the Stone and swears to get it at all costs. He asks Greenberg if he told anyone about the Stone and Greenberg admits to telling his lawyer dad.John drags the lawyer through a warehouse and ride up a fright elevator to a floor where Greenberg is lying on the ground at Kelp's feet beaten and bloodied. They press him and Greenberg recalls that his father told him he could sell the Stone and use the money to free Greenberg. The lawyer denies this and Kelp drags Greenberg to the elevator shaft. The lawyer glares at John, saying he doesn't have it in him, so John drags the lawyer to the shaft as well. John backs off. The lawyer gloats that he was right about John. John says that some people aren't willing to do such things, but some people are, and calls over a thug wearing a stocking over his head. Chicken grabs Greenberg and holds him over his head by the shaft. The lawyer swears he does not have the Stone and asks John to stop this. Finally, John tells the thug to put Greenberg down, but the thug drops him too close to the edge and Greenberg falls into the shaft. Kelp faints. John, stunned, gets punched by the thug who then heads for the lawyer. As the thug drags the lawyer toward the shaft, the lawyer tells them the Stone is in his safe deposit box and tosses them the keys. John picks up the keys. Kelp stands up. The thug turns out to be Stan. Greenberg, unhurt and hanging from a rope, threatens to tell on the lawyer to his mother.Kelp and John go to the bank. They see another customer sign a card and then the teller comparing the signature to what they have on file. Now at The Doctor's office, the lawyer giddily tells them that even if they use his key and forge his signature, they still wont get away with it because hes been tipping the bank staff very well over the years and everyone knows him by sight. The Doctor is not pleased. Kelp promises it will only take a few more days.At the back room of the bar, John presents a few plans - none will end successfully. Stan is late; there are too many construction projects in the area for a smooth getaway. Suddenly, John says, "Miasmo."A woman follows a well-dressed man, a banker, into an elevator and he presses a floor for her. She points out the regular pattern of lights that the floor indicator is showing, and how relaxing it is. This puts the man in a hypnotic trance. Meanwhile, John is at the bank to sign up for a safe deposit box. The woman tells the banker that when a man goes to his bank and says, "Afghanistan, banana stand," that the banker must do everything the man says. The banker, in a trance, agrees. Kelp gets a call that the banker has been successfully entranced and John says he has to go to the bank first thing in the morning before the trance wears off.John waits anxiously outside the bank, popping an antacid.Kelp, Stan and Greenberg meet The Doctor at a park bench. The Doctor tells them he has been convinced to fire them by the lawyer, who is sitting at the other end of the bench. The Doctor tells them he has already incurred a lot of expenses despite their failure and they will have to be satisfied with what he's already paid them. The Doctor and the lawyer get in their town car and head for the bank.John goes to the bank. The valet in the safe deposit vault is the hypnotized man. John checks his own box and then says, "Afghanistan, banana stand." John gives the man the lawyer's safe deposit key, the man retrieves the box for him, and John gets the Stone. John makes it out of the bank but hears sirens - it's a fire truck. As he walks away, the town car with The Doctor and lawyer, pulls up but they don't see each other. John walks a few blocks and sees the team in Kelp's locksmith car. They drive away cheering.