1986 was a year in the 20th century.
- Monday, March 3: A Western Union man delivers a letter written by Clara Clayton in 1893 to Marty McFly at Hill Valley High School.
- Wednesday, May 14: Marty McFly arrives at Doc's garage as it is about to undergo an estate sale, but soon hears the DeLorean time machine arrive in the driveway. Marty takes off to June 13, 1931.
- Thursday, May 15:
- 8:32 a.m:: Marty & Doc return from 1931, only to find that they are in 1986A in which the Tannen crime family rules Hill Valley. They subsequently depart once more for 1931.
- 2:15 p.m: Marty arrives back from 1931 a second time, but he has arrived in 1986B, an alternate timeline where Emmett married Edna, and has turned Hill Valley into a dystopian society. This leads Marty to do several things:
- Convince an alternate Jennifer to help him out of the crashed DeLorean
- Talk to several people around Hill Valley about the alternate timeline
- Get in trouble in three ways:
- Have an interview with Citizen Brown, in which he tries to convince him that he is from the original timeline, and that Citizen Brown should be a scientist.
- 5:30 p.m: George cleans the playback heads of his tapes, and is attacked by Biff shortly after. Marty and George discover this, and Marty confronts Biff. This leads Marty to:
- Discover Biff was being brainwashed
- Fight a mind-controlled Biff in Edna's lair
- Confront Edna
- Convince Citizen Brown that he is telling the truth
- Be captured, and thrown into the Citizen Plus ward
- Unknown: Marty and Doc return from 1931 one last time, and resume their lives in the real 1986.
- Friday: May 16: