Two men arrive, separately, in alleyways lit up by forks of lightning. Both are naked and one fares far better than the other. Both have crossed time but there reasons differ. One is a machine, a cyborg, sent back in time to kill the leader of the human resistance, John Connor, before he is even born, and the other has been sent back to stop him at all costs.
The Terminator works its way through all the Sarah Connors in the telephone directory, killing each one he finds but Kyle Reese knows where to find her. Even though he saves her in the bar, she is afraid of him as he forces her to go on the run with him. Eventually, the police catch up with them and Sarah is almost convinced that Reese is a psycho until the Terminator arrives and murders everyone standing between him and Sarah.
Once more on the run, and now understanding the enormity of what is happening to her, Sarah begins to look at her savior differently. He teaches her to make pipe bombs and tells her a little about the terrible life ahead for humanity as Skynet takes over the world. Kyle admits that he has loved Sarah for a long time, knowing her form the picture John Connor gave him. They make love but their love is shortlived as they are forced on the run again. This time, the Terminator catches up and, in tryign to protect her, Reese is killed. Sarah uses all her remaining strength to lure the Terminator through a machine factory, where it is crushed.
In the final scene, Sarah is sitting in a jeep somewhere in Mexico, recording words onto a tape for the child she carries, Kyle's child - John Connor. A small boy takes her picture and she pays for it. That photo is the picture John gave to Kyle Reese.