Fictional Timeline

After acquiring the DeLorean and modifying it into a time machine, Doc brings it to the Twin Pines Mall and tests it out by using a remote control to send it one minute into the future with his dog Einstein in it. He also shows Marty the major functions of the DeLorean: the flux capacitor, the time circuits, and the plutonium chamber that powers them. After refueling the DeLorean with plutonium stolen from Libyan terrorists (who previously stole the plutonium from a power plant), Doc prepares to travel into the future, but the Libyans unexpectedly arrive and shoot Doc. Marty uses the DeLorean to flee from the Libyans and is transported to 1955 after accidentally activating the time circuits, but without the needed plutonium to return to 1985. Once there, the DeLorean exhibits problems with the starter, and with its plutonium chamber empty, Marty hides the DeLorean behind a road sign and contacts the Doc Brown living in 1955. The two bring it to Brown's workshop.

Unable to obtain plutonium, Doc and Marty realize, from a fundraising flyer given to Marty earlier in the film, that the only source for the power needed to return the DeLorean to 1985 is a bolt of lightning that they know from history will strike Hill Valley Courthouse's clock tower at 10:04 PM on the coming Saturday, November 12. Doc installs a cable leading from the top of the clock down to the street to harness the lightning, and attaches a long pole and hook to the DeLorean to channel the energy into the flux capacitor once the hook makes contact with the cable while the DeLorean is accelerating at 88 mph. Despite setback involving the cable being disconnected by a fallen branch and the DeLorean having starter problems again, the plan succeeds, and Marty returns home, arriving eleven minutes before he left 1985 to warn Doc of his upcoming death since 1955 Doc wouldn't listen out of fear of changing history. With the DeLorean once again having issues with the starter, Marty is forced to run to the Twin Pines Mall, now called the Lone Pine Mall due to his actions in 1955. He is too late as Doc is gunned down while his other self escapes to 1955, leaving the Libyans to crash into a photo booth, but it is revealed that Doc wore a bulletproof vest and had listened to Marty's warning after all.

After returning Marty home, Doc travels with Einstein to October 21, 2015, where he upgrades the DeLorean with 2015 technology, replacing the plutonium chamber with a Mr. Fusion Reactor, and giving it the ability to fly. In the second film, he returns to 1985 to pick up Marty and Jennifer, telling them that they have to rectify a problem caused in the future when Marty's son commits a crime. While there, the DeLorean is stolen by Biff Tannen, who discovers that it is a time machine, and uses it to travel back to November 12, 1955, the same day as the climax of the first film, to give his past self a sports almanac which the young Biff uses to accumulate wealth from gambling. Biff returns the DeLorean to 2015, without Marty or Doc discovering his use of it until they return to 1985, which due to Biff's manipulation of history, has been transformed into a post-apocalyptic alternate timeline in which Biff is a wealthy casino boss and crime lord. Discovering from that this was caused by older Biff's use of the DeLorean and the almanac, Marty and Doc return to 1955 to prevent the younger Biff from acquiring it, thus restoring the original timeline. They manage to take back and destroy the almanac, but the DeLorean, with Doc inside it, is struck by lightning again, this time by accident, and due to a malfunction in the time circuits, and disappears. Unbeknownst to Marty, Doc is transported to January 1, 1885. Both the DeLorean's time circuits and flying capability are disabled in the process, though not the internal combustion engine.

Because suitable replacement parts to repair the DeLorean will not be invented until 1947, Doc hides the DeLorean in a mine, and leaves a letter to be delivered to Marty by Western Union in 1955, in which he explains what happened to him. Doc states he is happy in his new life there as a blacksmith, and requests that Marty not attempt to retrieve him, but instead to return to 1985 and destroy the DeLorean, believing that it has brought them and the world nothing but disaster. However, Marty and 1955 Doc learn that just nine months after arriving in 1885, Doc will be murdered by Biff's great grandfather, Buford "Mad Dog" Tannen, on September 7, 1885. For this reason, the 1955 Doc and Marty agree to have Marty travel back in time to 1885 to prevent Doc's murder. After retrieving the DeLorean from the mine, repairing its time-travel ability, and replacing its since-disintegrated tires with whitewalls (although they could not restore its flight systems), Marty travels to 1885, but the DeLorean's fuel line is damaged soon after he arrives there. After encountering his ancestors, Marty decides to use the alias Clint Eastwood. After meeting up with the 1885 Doc, the fuel line is repaired, but their experiments with creating modern fuel from whiskey destroys the fuel injection manifold, leaving the car unable to travel under its own power. After trying a few ideas (such as pulling it with horses), they resolve to use a steam locomotive to push the DeLorean up to 88 mph. They learn that in order for the locomotive to reach 88 mph, the run would have to be on a flat, straight track with no cars coupled behind it and with the boiler's temperature risen to dangerous levels. Doc replaces the 1955-style wheels with cast iron train wheels that fit on the track rails.

Doc and Marty plan to make their run on a flat, straight section of track leading to an unfinished bridge over Shonash Ravine. While making their plans, Doc saves schoolteacher Clara Clayton from falling into Shonash Ravine. They realize in the original timeline, Clara fell to her death in the ravine, which was renamed Clayton Ravine. After her rescue, Doc and Clara begin to fall in love. Marty and Doc continue their plan, in which the Mr. Fusion unit will provide the power required to activate the flux capacitor and make the jump through time once the stolen locomotive and the DeLorean reach 88 mph. Their plan is successful, and upon reaching the end of the track, the DeLorean disappears to 1985 with Marty, though Doc decides to stay behind with Clara, since "Mad Dog" Tannen is arrested for a stagecoach robbery, and Doc's murder is prevented. The locomotive falls down the cliff.

Back in 1985, the DeLorean arrives on the now-completed bridge and crosses over the ravine, now called Eastwood Ravine on account of his exploits in 1885. The DeLorean becomes stuck on the tracks, and Marty barely manages to escape before the DeLorean is completely destroyed by a freight train. Later, Doc, Clara, and their children: Jules and Verne, appear in the same location where the DeLorean was destroyed, piloting a new time machine in the form of a steam-powered train. After picking up Einstein, the couple and their children depart for an unknown time period.