After rescuing Marty in 2035 from Officer Griff Tannen, and preventing him from getting a sage implant and a personality rewrite by Commissioner Wilson, Jennifer drove the second DeLorean time machine back to March 4, 1986.
Doc dropped Marty and Jennifer off at the McFly residence, and then took the DeLorean back to 1893 to reunite with his family. Shortly afterward, the police arrest Douglas J. Needles for crashing into the delivery truck. They don't believe his claims that Marty McFly and Jennifer Parker were involved, since there was no DeLorean near the crime scene, and Marty and Jennifer were both asleep in their beds.
Needles used his phone call to call Marty a chicken, and Marty was unfazed, telling him that he needed to change his tune.
The next day, Marty and Jennifer saw the new Clint Eastwood movie, and Marty arrived home in the late evening. His parents admonish him for being late, but he hugs them, and lets them know that he is finally over his depression caused by Doc's absence.
On May 14, 1986, Doc's garage is under foreclosure from the bank, and the contents within are being put up for sale in an estate sale. Marty goes to the estate sale to try to get his father, George McFly, who is sorting the merchandise for the bank, to get the bank to stop the sale. George tells Marty that there is no way that it can be stopped, as Doc hasn't paid taxes on his garage, and neither he nor the bank haven't seen him for six months.
Doc wasn't in the time machine, but Marty learned, from a stack of newspapers kept by Edna Strickland, that Doc had been killed by Kid Tannen in 1931. He dressed in a suit that his girlfriend's father had, in order to blend in, and took the DeLorean to 1931.
- Back to the Future (IDW Publishing)