Running away from home, Verne uses the DeLorean to travel back in time. When Doc, Marty and Jules go after him, they arrive in the middle of the Civil War where Jules and Verne get caught up on different sides.

Doc causes another power cut in his lab whilst trying to invent something. Jules and Verne are annoyed because their toy car racing has been interrupted (it runs on electricity) and Clara is annoyed at the lack of power as well. Feeling that his family has become too dependant on technology since they moved to the 20th Century, Doc uses the DeLorean to take his family back to Medieval England. The family are not happy, especially when Doc sends the DeLorean several hours into the future so there is no way they can go home until then. Clara walks off and after meeting some Medeival women washing in the river she meets Lord Biffingham of Tannenshire. Biffingham takes a shine to Clara and when she turns him down he kidnaps her. Doc tries to save her but eneds up being kidnapped as well. Biffingham imprisons Clara in his tower and decides to marry her - once she has become a widow! And he plans her to be a widow very shortly by challenging Doc to a joustling match.

Doc and the boys travel back to prehistoric times to test a new invention and Doc stops a meteor from colliding with Earth. They don't realize they changed history until they return home and find a civilization where dinosaurs rule!

Marty makes an emergency trip back to Salem, Massachusetts in the DeLorean to deliver a spare flux capacitor to Doc and the family. While Doc installs it to fix the train, Marty, Clara and the boys go into town, where Marty gets accused of being a witch.

Marty and Doc head to Ancient Rome, unaware Jules and Verne are joining them. While the boys cause trouble, Marty gets mixed up in a chariot race with Bifficus and Doc gets thrown to the lions.

After Jules insults his intelligence and comments that he can't really be a part of the family, Verne starts to think his real father is Benjamin Franklin. Unfortunately, this leads to Verne ruining Franklin's famous electricity experiment and it's up to Doc to set things straight.

Looking to cure Marty's athlete's foot, Doc and Marty travel back in time to locate an extinct frog in South America, where they have to stop Biffando from stealing the Incas' gold.

Marty takes the place of his ancestor, pitcher Pee Wee McFly, to help his team win a 1897 Pennant game. But a nasty gangster named Diamond Jim Tannen wanted Pee Wee to lose.

It's Doc and Clara's anniversary and the kids get them tickets for a cruise, which takes place in 2091 and takes them into space. Unfortunately, Ziff Tannen sabotages the cruise ship.

It's Christmas time so the Brown family and Marty go to 1800s London to celebrate. Unfortunately, the boys lose the key to the DeLorean to a pickpocket and Clara, a toy shop manager and his family get thrown into prison by Ebiffnezer Tannen.

When Doc was four, he fell into a river during a fishing trip and has had a fear of it happening again ever since. After the boys learn about this, they and Marty try to change it. But they regret it when it leads to a mishap with a stunt plane, causing young Emmett Brown to become a famous daredevil.

Jules and Verne pull a string of April Fool's Day pranks on Doc, tampering with his inventions. Unfortunately one of them, the Brain Wave Analyzer, causes Doc to think his days in science are over and he retires.

Marty, Jules and Verne head back to the 1850s, where they meet Jules and Verne's maternal grandparents, Daniel and Martha. Unfortunately, Martha falls in love with Marty instead of Daniel, and Clara is in danger of never existing. Things get worse when Martha is kidnapped by Wild Bill Tannen...