Depressed cab driver Vince McKee—bored with his job with its ghastly fares, out of love with wife Ros, and disrespected by his schoolgirl daughter Katie—encounters Colin Vine, an old friend just released from incarceration for armed robbery. Ros detests him, but Vince takes up his invitation to play poker at the house of a man known as The Horse. The Horse offers Vince a cryptic and clearly illegal driving job, though it does come with a smart new car. The first two jobs go well, albeit not entirely without incident. The next, however, is far more sinister, as Colin attacks a man and bundles him into the boot.

Vince is horrified to see Colin throw his victim into a pit, though Colin tells him he should be happy to be earning extra money. Early the next morning, Vince rescues the man and drops him off at casualty, claiming to have found him in the road before driving off. Ros becomes suspicious of blood on her husband's shirt but he flees her interrogation by making an unannounced visit to their estranged son Tim, who has joined a sect. Upon return, Vince is visited by police, who tell him that the man he saved, Joseph Paslowski, is a dangerous gangster. He goes to see The Horse, whose men are punishing Colin for apparently failing to kill Paslowski

With Paslowski now out of his coma, the police visit Vince again. After visiting the badly injured Colin and asking to leave the gang, he tries to bribe a colleague to give him an alibi but Kev squeals and Vince is arrested. He confesses everything and is offered a deal — to carry on working undercover and inform the police of their next planned job, the robbery of a Chinese supermarket. The McKees are put under witness protection and given new identities, angering Ros and Katie. Preparing for the robbery, Vince is amazed to see that Colin will be taking part and tells him to back out as the police will be waiting. Everything goes to plan and Vince hears from Tim that he wants to come home. Does this signal an end to the nightmare for the driver or are he and his family still in danger?