Dexter Riley and his friends attend the small, private, Medfield College, which cannot afford to buy a computer. The students persuade wealthy businessman A.J. Arno to donate an old computer to the college. Arno is the secret head of a large illegal gambling ring, which used the computer for its operations.
While installing a replacement part during a thunderstorm, Riley is zapped 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 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, a trigger word causes Riley to unknowingly recite on television details of Arno's gambling ring. Arno's henchmen kidnap Riley and plan to kill him, but his friends help him escape. During the escape, Dexter suffers a concussion which, during the tournament final against rival Springfield State, gradually returns his mental abilities to normal; one of Riley's friends, Richard Schuyler however, is able to answer the final question ("What is the Geographic center of the contiguous United States?"). Medfield wins the $100,000 prize, and Arno is arrested.
- Kurt Russell as Dexter Riley
- Cesar Romero as A.J. Arno
- Joe Flynn as Dean Higgins
- William Schallert as Professor Quigley
- Alan Hewitt as Dean Collingsgood
- Richard Bakalyan as Chillie Walsh
- Debbie Paine as Annie
- Frank Webb as Pete
- Michael McGreevey as Schuyler
- Jon Provost as Bradley
- Frank Welker as Henry
- W. Alex Clarke as Myles
- Bing Russell as Angelo
- Pat Harrington as Moderator
- Fabian Dean as Little Mac
- Fritz Feld as Sigmund van Dyke
- Pete Ronoudet as Lt. Charles "Charlie" Hannah
- Hillyard Anderson as J. Reedy
- David Canary* as Walski
- Robert Foul* as Police desk sergeant
Not credited on-screen.*
This is one of the extremely rare on screen appearances of voice actor Frank Welker.