Kicking off in the post-apocalyptic future where the machines have risen and enslaved mankind, resistance leader John Connor (Jason Clarke) sends his friend, Kyle Reese (Jai Courtney), back in time in time to save his mother, Sarah Connor (Emilia Clarke) from a Terminator assassin.
But Kyle finds the past is not what he was expecting (ie the original Terminator movie), because the time-stream has been changed dramatically by Sarah being saved, as a young child, by a Guardian android (Arnold Schwarzenegger) sent back (by persons unknown) to protect her.
In this new timeline, Judgment Day has been delayed to 2017, when it will come about with the release of Cyberdyne's "killer app" Genisys, which is supposed to sync up every computer-powered device on the planet.
The simple plot of Terminator: Genisys is masked under an unnecessarily convoluted story (that quite possibly doesn't even hang-together) and an abundance of loud explosions and physics-defying set-pieces.
A total lack of empathy for any of the main characters reduces the experience of watching the movie to that of watching someone else playing a video game.
There are some clever ideas in there and visceral moments of excitement, but ultimately it's a very hollow and forgettable, albeit breathlessly paced, couple of hours (although not as forgettable as Terminator: Salvation).
A fast food meal of a movie, you might find yourself enjoying it for what it is, while it lasts, but 30 seconds after the credits roll you'll have a hard time remembering anything more than bright flashing lights and sonic booms.
And don't miss the sequel-baiting scene dropped in mid-credits that pretty much undermines everything that has just happened.
Of the three women to play Sarah Connor on film and television (Linda Hamilton, Lena Headey, and Emilia Clarke), Emilia Clarke is the least convincing as a badass, and Jai Courtney is no Michael Biehn either.
Doctor Who's Matt Smith pops up for a few scenes as a key Terminator, sporting a bizarre mid-Atlantic accent that sounds like it's trying for American but got lost along the way.
The film's attempts to homage the original couple of movies - both subtly and overtly - do nothing more than draw attention to how weak this one is in comparison.
I think it's about time this franchise declared it won't be back!