In the first film, Back to the Future, Dr. Brown shows Marty the time machine, in the form of a DeLorean, which he had invented after stealing plutonium (used as fuel for the vehicle's time circuits) from Libyan terrorists, who wanted him to build a nuclear weapon. During this exchange, the doctor is shot by the enraged terrorists, and Marty escapes from them in the time machine, accidentally traveling back to 1955. There, he encounters his teenage parents and disrupts the course of their meeting. He contacts the 1955 Dr. Brown and with his help, reunites his parents, and travels back to an alternate 1985, where his father George is a novelist, and Biff, his father's high school bully, becomes their caretaker. He also finds out that Dr. Brown is still alive and that he had worn a bulletproof vest after Marty had warned him about his fate in 1955.