Plot
Hitman Arthur Bishop sneaks into the home of a Colombian cartel boss and drowns him in his own pool. Upon returning home to Louisiana, he meets with his friend and mentor Harry McKenna.
Bishop is assigned by his employer Dean to kill Harry. Dean says this is due to a failed mission in South Africa, in which his team of assassins were killed; since the mission was known only to Dean and Harry, Dean attributes the failure of the mission to Harry ratting them out to the South African police, making him a threat. Bishop reluctantly kills Harry and makes it look like a carjacking. At Harry's funeral, Bishop meets Harry's estranged son Steve, whom he later stops from killing another carjacker in revenge.
Steve asks Bishop to train him as a hitman; Bishop thus takes him under his wing and gives Steve his next contract, fellow assassin Burke. He also brings Steve to another contract killing to observe. Ignoring Bishop's instructions to overdose Burke with Rohypnol, Steve goes with him to his house and attempts to strangle the much larger man with a belt, imitating Bishop's last killing. He barely manages to kill Burke after a lengthy fight. Dean expresses disapproval of Bishop using Steve, which violates the rules of the contract.
Bishop's next target is cult leader Andrew Vaughn, whom Steve suggests they inject with adrenaline to simulate a heart attack. However, Vaughn's doctor administers an IV of ketamine, which would inhibit the adrenaline's effects. The two choke Vaughn to death instead with a mini camera.
They are discovered by the guards, shoot their way out, and fly home separately to avoid suspicion. At the airport, Bishop catches sight of a hitman who was supposedly killed in the South Africa mission that Harry sold out. The hitman reveals that Dean engineered the failed mission to cover up his own shady dealings. Bishop realizes Dean framed Harry and tricked Bishop into killing him.
Angry at being tricked, Bishop takes down the team Dean sends to kill him and helps Steve when Steve is also ambushed. Steve finds his father's gun in Bishop's belongings, and realizes that Bishop killed him. Bishop and Steve kill Dean together. Bishop plans to disappear with a new identity now that his employer is dead. When they stop for gas, Steve, in revenge, blows up the truck with Bishop still inside.
Steve returns to Bishop's home and does two things Bishop told him not to: plays a record on the turntable and steals Bishop's 1966 Jaguar E-Type. As he drives, Steve finds a note on the passenger seat; it reads: "Steve, if you're reading this, then you're dead." The car then explodes, killing him. Another explosion from the rigged turntable destroys the house. Bishop had seen Steve carrying his father's gun, and knew beforehand that Steve would betray him.
Security footage at the gas station reveals that Bishop had escaped from the truck before the explosion. He gets into a spare truck and drives away.