Set after the events in Terminator 2: Judgment Day (1991), Sarah Connor and her son, John, try to stay under-the-radar from the government, as they plot to destroy the computer network, Skynet, in hopes of preventing Armageddon.

Sarah Connor: [Season 1 opening Intro] In the future my son will lead mankind in a war against Skynet, a computer system programmed to destroy the world. It has sent machines back through time. Some to kill him, one to protect him. Today we fight to stop Skynet from ever being created. To change our future. To change his fate. The war to save mankind begins now!
Male Voiceover: [Season 2 Opening Intro] In the future a computer program called Skynet will declare war on the human race. Machines have travelled back in time taking human form to terminate John Connor, the future leader of the resistance. Sarah Connor, John Connor's mother, teacher, and protector. Cameron, a terminator reprogrammed to defend them at all costs. Derek Reese, John's uncle and a commanding officer with the resistance. Together they fight to stop Skynet from ever being created. The battle for our tomorrow starts today.