It's 1978 and 12-year-old David Freeman is knocked unconscious after taking a tumble in the woods. He wakes up and heads for home only to find strangers living there. It's now 1986 and he's been missing for eight years. NASA believes he's been abducted by aliens and want to use in him in their research. But with the guidance of a strange unseen entity he discovers a top-secret spaceship and, with the help of Max the computer, sets off on an incredible mission to get back to the past where he belongs.