Dexter Riley (Kurt Russell) and his friends attend small, private Medfield College, which cannot afford to buy a computer. The students persuade wealthy businessman A.J. Arno (Cesar Romero) to donate an old computer to the college. Arno is secretly the head of a large illegal gambling ring which used the computer for its operations.
While installing a replacement computer part during a thunderstorm, Riley receives an electric shock and becomes a human computer. He now has superhuman mathematical talent, can read and remember the contents of an encyclopedia volume in a few minutes, and can speak a language fluently after reading one textbook. His new abilities make Riley a worldwide celebrity and Medfield’s best chance to win a televised quiz tournament with a $100,000 prize.
Riley single-handedly leads Medfield’s team in victories against other colleges. During the tournament, on live television, a trigger word causes Riley to unknowingly recite details of Arno’s gambling ring. Arno’s henchmen kidnap Riley and plan to kill him, but his friends help him escape by locating the house in which he is being kept, posing as house painters to gain access, and sneaking him out in a large trunk. During the escape, Riley suffers a concussion which, during the tournament final against rival Springfield State, gradually returns his mental abilities to normal; however, one of his friends is able to answer the final question (“What is the geographic center of the contiguous United States?” with the answer “Lebanon, Kansas”). Medfield wins the $100,000 prize. Arno and his henchmen are arrested when they attempt to escape the TV studio and crash head-on into a police car.