Preston Tucker is a heartland dreamer who wants to build a better mousetrap. When the film opens, we watch a newsreel about his innovative military vehicle for World War II that was ultimately rejected by the military. Nevertheless, the war's over now, and Tucker wants to build an innovative automobile with forward-thinking mechanical and safety features that seem bold and flashy in the 1940s but will soon become standard in all automobiles.
We watch Preston Tucker win people over again and again. First the investor Abe Karatz, who rejects his pitch to start a car company only to come around once Tucker lands an article about the prospective car in PIC magazine. That article brings mail sacks full of letters from across the country in adoration of the striking new car, and Tucker sets out to build the thing. His company acquires the largest factory in the world, over in Chicago, and he gathers a board of directors and some small-fry investors to launch the company. The only issue? Tucker doesn't even have a prototype of the car.
So, Tucker and his crew spend the next 60 days before the factory opens building a prototype. It's not even complete by the time of the big unveiling event, as Tucker and his engineering crew tweak it behind the curtain where it's supposed to be unveiled. After springing a gas leak and starting a small fire, they finally unveil the car to a roaring crowd and adulation from the press to a raucous event in that Chicago Tucker factory. The car is a hit.
But while Tucker starts out on a publicity tour to promote his soon-to-be-produced car, the Tucker Corporation's board of directors sets out to redesign the car to make it more conventional and, they believe, more cost-effective. Never mind the fact that their redesigned version of the Tucker car will sell for twice as much as the price originally advertised. When Tucker gets a call from his wife Vera about the machinations of these executives, he rushes back home to take control of the operation again. When he confronts RJ Bennington, chairman of the board, he enters an intense power struggle for the future of his car.
So Tucker goes back to Ypsilanti to plan his next move. While there, he gets a call from Howard Hughes, who brings Tucker to his home to tell him about a helicopter company in Buffalo with a surplus of steel and a good aluminum engine. Tucker and his team retool the engine to work in the car, and get a magnificent vehicle out of it. Against Bennington's wishes, they resume production on the original design, but Tucker runs into more trouble. Abe tells Tucker that the factory is bugged and the FBI is after him. It turns out that Senator Homer Ferguson of Michigan is trying to sink Tucker because of his threat to the Big Three auto companies.
The SEC ultimately raises a fraud lawsuit against Tucker for taking millions of dollars from investors without actually building a car. It's a ridiculous charge, but it puts the Tucker company out of business and gets the Chicago factory taken away by the government. During Tucker's trial, the SEC makes a series of false allegations about his books and Abe's own past as a felon is carted out. But it doesn't matter. Tucker gives a compelling speech about innovation and the American dream, causing the jury to find him not guilty. Outside of the courtroom, 50 Tucker cars take attendees of the trial for rides while Tucker tells Abe that they achieved their dream, even if the company is dead.
