Perfect 80s move. Michael J Fox plays Marty McFly, a high school kid, who is for some reason best friends with an older man named Doc Brown. They use a DeLorean to travel back in time to the fifties. Marty meets his mom and dad (fifties version) and then all the important plot stuff happens. He has to go find Doc Brown (fifties version) in order to fix everything and get back home. SO GOOD.
See the John Mulaney Back to the Future bit if you would like a funnier/wittier summary.