Pilot James T. Hoffman is busted by the FBI when he arrives in the United States with a large amount of cocaine in his airplane. His wife Ellen, Judy Greer Hoffman, and their two sons are with him, having accompanied him on the flight to Bolivia. He agrees to become an informant and the FBI relocates him and his family to San Diego. Special Agent Benedict Tisa, Corey Stoll, acts as his handler and continually pressures him into setting up his boss, Morgan Hetrick Morgan Hetrick, who has millions of dollars in overseas accounts from trafficking narcotics. Hoffman attempts to play both sides.
Hoffman meets John DeLorean, Lee Pace while trying to start his car, discovering that he's his next door neighbor. DeLorean is designing the ultimate car of the future, after his continued dissatisfaction with the automobile industry and his role in it. Hoffman’s and DeLorean’s families become friends. Hoffman tells his wife Ellen, Judy Greer Hoffman, that he's an informant, leading to tension between the two.
DeLorean throws many parties in order to raise funds for his new car. He receives $600,000 from Johnny Carson, who calls DeLorean during one of his parties and is put on speaker phone, where he complains about how the new car has continually broken down. Hoffman brings Hetrick to the same party in order to introduce him to DeLorean after having bragged to him about DeLorean's new car. The two of them, along with Hetrick's girlfriend, Erin Moriarty snort cocaine laced with PCP, leading to disruption.
Hoffman works for DeLorean who struggles to raise funds and is in a large amount of debt. DeLorean asks him to raise $30,000,000. Hoffman informs Tisa that DeLorean wants to move cocaine in order to raise the money in exchange that he and his family will be safe from any criminal prosecution and that he will no longer be required to work for the FBI. Hoffman introduces DeLorean to Hetrick and Tisa who poses as a drug dealer in order to bust them both. They all agree to the deal. Problems arise when DeLorean can't raise any money for the initial deal but Hoffman convinces Tisa to loan DeLorean federal money as his undercover persona in order for the deal to go through.
Hetrick and Erin Moriarty are arrested by Tisa and other agents when they deliver the cocaine. Hoffman drives DeLorean to a hotel in order to receive his money from the deal, with DeLorean unaware that he's actually meeting undercover federal agents. DeLorean is arrested after going to a room and completing the deal. Hoffman is seen testifying against DeLorean in court in flash-forward scenes throughout the film. At the end of the film, while on the stand, Hoffman is unable to conclusively say whether or not DeLorean was the one who suggested the deal. DeLorean is acquitted of all charges.
Tisa informs Hoffman that he'll make sure witness protection send him and his family to Boise, Idaho. DeLorean and Hoffman meet in a cafe where DeLorean hands him keys to one of the cars he had been designing sitting outside, as well as a briefcase for his inconclusive testimony. Hoffman gets in the car and opens the briefcase which contains a large amount of money. He puts the key in the ignition and turns it but the car does not start.
