This is the fourth movie in the Terminator franchise. It came out in 2009, a month or so after the conclusion of the TV series "The Sarah Connor Chronicles," but as far as I can tell, it is not a part of that continuity. (And I didn't see it until 2015, a couple days after the release of "Terminator Genisys," which I have no idea if or when I'll get to see.) "Salvation" does seem to be part of the continuity of all three previous films. (In this movie, John Connor is apparently married to a woman named Kate, who was played in the third movie by Claire Danes, and in this movie by Bryce Dallas Howard. But I would have had no idea it was the same character if not for Wikipedia.) Also, it seems like the timeline has once again been screwed around with, and I have no idea how that happened. At least this movie doesn't involve time travel.
It begins in 2003, when a doctor from Cyberdyne (played by Helena Bonham Carter) convinces a murderer on death row to donate his body to a scientific project. Then the story flashes forward to 2018. John Connor (Christian Bale) is part of a Resistance team that acquires some information that could help them take down Skynet. He's not yet the leader of the Resistance, though he's obviously a cult hero, because everyone knows the prophecies about him. Also he makes occasional radio broadcasts that seem to be popular. Anyway, he's the sole survivor of his mission. He demands to be taken to the command center of the Resistance, where he offers to test the info his team had retrieved and transmitted to command, before they all died. Meanwhile, in L.A., a guy named Marcus Wright meets a teenager named Kyle Reese (Anton Yelchin), and a young girl named Star. Honestly, at first I had no idea who Marcus was, because I'm terrible at remembering faces. And by this point I had already forgot about the opening scene. But after awhile I remembered it, and thought, "Wait, is that the guy from the opening scene?" And it was. (I absolutely can't remember if his name was even mentioned in that scene, because my memory sucks with names, too. And with pretty much everything.) Although of course there's no way to forget the name Kyle Reese; we all know that he's going to be John Connor's father, someday. So of course he's super important. He seemed like a cool enough kid, with potential to be a badass. (Star has the same potential.) But for now, Kyle is basically a living MacGuffin. Marcus and Kyle and Star begin traveling toward San Francisco, where Skynet is headquartered. Eventually, Kyle and Star and a bunch of other people get abducted by a Skynet robot, and Marcus wants to rescue them. Meanwhile, Connor is also looking for Reese, and sends out some fighter planes to attack Skynet planes, or whatever. And one of the Resistance pilots, Blair Williams (Moon Bloodgood, whom I know from Falling Skies), is forced to eject when her plane is hit. She later meets Marcus, and takes him back to her base, to meet Connor.
There's a twist about Marcus that I'd suspected for a while before it was confirmed, but I don't want to reveal it (even though it's almost impossible not to predict). I'll just say he and Connor both eventually go to San Francisco to rescue the prisoners (most importantly Kyle). And Connor learns that Skynet has created a new type of Terminator, the T-800 (which is of course the type that will later be sent back in time to kill his mother). Also, the leader of the Resistance wants to use the info Connor's team had retrieved, and launch an all-out attack on Skynet, but Connor needs time to rescue the prisoners, so there's some conflict there. (I also had a suspicion about that information, and it turned out I was right, but I won't spoil that, either.)
And... I'm really not sure what else to say. I guess it works okay as a sort of post-apocalyptic action movie, and it's a worthy endeavor to depart from the formula of the earlier films. And yet, I wouldn't exactly call the experiment a success. It's not a bad movie, it's just nowhere near as good as the first two. Um... anyway, there are perhaps some unanswered questions... though it's possible they were answered in tie-in materials such as novels or comics, none of which I've read and have no interest in reading. Also, this was supposed to be the first movie in a new trilogy, I guess, and that never materialized. (The fifth movie is another reboot of the franchise.) So, whatever... I don't really care. I'm glad to have seen this, but I can't quite imagine ever feeling the need to see it again.