In Las Vegas, as part of a robbery plan that ex-convict Chuck Wheeler and his cellmate, Mike Bennett, concocted while in prison, Chuck observes how casinos disburse their cash receipts to a bank’s armored car. To launder the heist’s take, Chuck intends to hook up with racketeering boss Joe Darren, who is having an affair with Mike’s wife, nightclub singer Vi Victor. Chuck then goes to a hill by a sparse stretch of desert highway and shoots out the passenger tire of Darren’s passing limousine, which forces the car to skid into the lot of a lone gas station. Chuck visits Vi that night after her show, but she refuses to speak to Darren for him, until Chuck reveals that he knows of their relationship and threatens to tell Mike. Later, when Vi telephones Darren and mentions that Chuck was responsible for the tire incident, Darren agrees to see him. Chuck meets Darren at the trailer of Chuck’s accomplice, petty criminal Lou Largo, and explains that the gas station in the desert is on the daily route that the armored truck takes to a Los Angeles bank. He admits to having shot out the tires of several cars at the same spot to determine how to get the armored truck to slide to a stop at the gas station. Chuck informs Darren that the heist, which they have planned for after the profitable New Year holiday, will be in excess of two million dollars, and Darren agrees to help. Later, Lou rigs Chuck’s short-wave radio to pick up the police transmissions from brief distances. Lou and Chuck then follow the armored truck and tape-record the regular check-ins between the truck and police dispatch. While Darren convinces Vi to help with the robbery, Chuck continues to monitor the armored truck’s daily trips, marking the time it passes the gas station. Chuck then sets Vi up at a motel across from the gas station, the Stage Coach Inn, run by husband and wife Steve and Ann Thomas, and over several days, Vi keeps a detailed log on traffic. Ann befriends Vi, who comes to envy the other woman’s security and happy family life with Steve. When Chuck arrives at the inn a few days later and checks in under an assumed name, Vi reports the traffic movement and that every day two policemen stop by the inn for coffee just twenty minutes after the armored truck goes by. Vi and Chuck are startled when Darren shows up that evening with the news that Mike has escaped from prison. Vi admits that she sent Mike a letter informing him that she intended to divorce him and marry Darren. Darren is outraged, but Chuck insists that the operation proceed and offers to protect Vi if she will run away with him to Mexico after the robbery. A statewide manhunt begins for Mike, who gets to Lou’s trailer and forces him to reveal Vi’s whereabouts before knifing him to death. Meanwhile, Ann invites Vi and Chuck to the inn’s New Year’s Eve celebration and asks Vi to sing. Later that day, Vi follows Chuck to his hilltop perch and pleads with him not to hurt Ann and Steve during the robbery, then agrees to accompany him to Mexico. That night while Vi and Chuck are at the party, Mike finds Darren and demands he drive him to the inn, before shooting him. When Vi and Chuck return to her cabin later, they are startled to find Mike. Chuck is angered over Lou’s murder and calls off the robbery, but Mike insists on taking Lou’s place. The police arrive shortly thereafter to report the discovery of Darren’s body, but only Ann and Steve are questioned. The morning of the robbery, Chuck situates himself on the hill as planned and shoots out the armored truck’s tire, and the driver reports their stop to the police dispatch as the truck skids into the gas station. Meanwhile, Mike ties up Ann and Steve and dresses as a mechanic, then guides the truck into the garage, where he shoots the guards. Vi gets hysterical when Mike declares he is killing Ann and Steve and Chuck agrees with the idea. Mike knocks Vi out and Chuck takes the Thomases out to the back of the inn. With only moments before the police are to make their regular coffee stop, Mike and Chuck don the guards’ uniforms, change the truck’s tire and continue on the route using the recorded check-in tapes to radio police headquarters. At the dispatch center, however, the police note that the truck is using old codes, not the codes issued for the new year. They report that the last correct check-in was just before the tire blowout at the inn and order roadblocks set up along the route. When Chuck and Mike spot the roadblocks, they hastily turn back to the inn. A police squad meets them there, and in a blazing shootout, Chuck and Mike are killed. After Vi revives and weeps over Chuck, Ann and Steve appear to reveal that Chuck let them go. As the police prepare to arrest Vi, Ann and Steve assure her they will testify on her behalf.