There was something wrong that could only be fixed by time-travel.
So we took the Terminator, you know, Arnold Schwarzenegger, and we split him into three robotic units, only one of which was humanoid. I was assigned to go with the one that was a robot Jeep, a four-wheeled all-terrain robo-car. The overhead lights on the rollbar were actually little eyes that looked back and forth. We traveled through time-- I don't know if we were coming from the past or the future but we traveled to a point in time where the human race had been largely destroyed by some sort of cataclysm-- something environmental, I think.
Jeep-Arnold and I needed to retrieve some sort of specialized part to take back to our own time; that was our mission. When we arrived at the place where it supposedly was, we found ourselves in some sort of lightly mountainous part of California-- somewhere in the Sierra foothills, maybe, or Mendocino County. There, two small groups of survivors were engaged in conflict against each other. The only difference between the two groups that we could detect was that one group was larger and had better technology-- they were managing to produce their own electricity, had better guns, etc. They were extremely hostile and they had the part we needed.
The other group was smaller, lived very rough and simple existences, and were being hunted into extinction by the larger group. We ended up joining with them mainly because they were less hostile than the larger group, the group that had the part we needed. Initially, I thought about trying to teach the small group several things they could easily do to help them fight back against their enemy and to improve their own lives, but it was clear that anything I gave them, they would just use to be as horrible to the other group as the other group was being to them. They wanted germ warfare, for one thing.
Ultimately, they gave me a lever-action rifle and a handful of bullets and I went on a foray against the other humans to try to get the part. There was some sniping and a lot of sneaking, but they eventually caught me. They could tell I was a time-traveler, I guess, and somehow just by knowing I was a time-traveler and having caught me, they suddenly knew all sorts of high-tech ways to finally exterminate their enemy, the smaller, simpler group of humans. So they set off to do it once and for all. I managed to slip out of whatever they'd captured me in, it was a cage I think, and I grabbed the part-- they were all off on their extermination mission-- and ran back to Jeep-Arnold. He wanted me to jump in and go back through time with him-- "Who cares what happens to these people? We have the part!"-- but I, in totally cheesy movie-of-the-week fashion, told him to go back without me, to take the part and leave me behind, because I had to go try to stop the massacre, I couldn't leave without making some sort of attempt at peace here.