★★☆☆☆

M, 126 minutes. Now playing

Director: Alan Taylor

Stars: Arnold Schwarzenegger, Emilia Clarke, Jason Clarke, Jai Courtney

Early on in Terminator Genisys, the blockbuster-sized fifth instalment of the science-fiction series that debuted 31 years ago, the heroic leader of the human resistance against the machine armies, John Connor (Jason Clarke), reminds the soldier he's sending back to 1984, Kyle Reese (Jai Courtney), that the woman he must protect, John's mother, is just an innocent young waitress. "What?" replies Kyle – the child of post-apocalyptic war doesn't know what a waitress is.

That's one of the final moments when this lumbering, sometimes incomprehensible beast of a movie makes knowing sense its own convoluted tracks. Complex in structure but lacking in creativity, Alan Taylor's film is meant to ignore the latter Terminator movies not directed by James Cameron, 2003's Rise of the Machines and 2009's Salvation, but it's hard to see the connection between the rigorous focus of Cameron's two original successes and this mishmash of familiar franchises (The Matrix, superheroes).

The storyline basically involves various people time-travelling to change history's outcome by stopping the various Terminator models, including Arnold Schwarzenegger's T-800, sent to change it. At one point a character tries to explain what is happening by using the phrases "nexus point" and "quantum field" in the same sentence, which is not exactly helpful.

What you're left with is John's mother, Sarah Connor (Emilia Clarke from Game of Thrones) being anything but a waitress. Armed and dangerous, she rescues Kyle upon his arrival, which is a neat spin upon the man saving the day. But their relationship devolves into a bad romantic comedy, as they banter about fate and memory. Both Clarke and Courtney are good with militant forcefulness but lacking in anything more subtle.

Sarah calls Schwarzenegger's "good" Terminator "Pops", and it's a guardian figure – don't bother asking who sent or programmed it – that makes dispassionate observations and participates in endless battles between close to indestructible creations. "Did you mate?" the ageing machine asks Sarah, knowing Kyle is to be John's father in established Terminator history, and it's one of the few times the blunt impact of the film is actually amusing.

Taylor, a prolific television director who previously helmed 2013's Thor: The Dark World, applies some vigour and physicality to his numerous action sequences, but it's hard to overcome a cynical outlook that allows established characters to be recycled into new adversaries amidst helicopter chases and the requisite acts of sacrifice.

The stripped-down momentum of Cameron's very first Terminator, the struggle to simply stay alive against a nightmarishly unstoppable adversary, has been irreparably lost, and revisiting it only makes clear what's now lacking. Like Arnold Schwarzenegger, Terminator Genisys is ageing, overly inflated and confusing.

CRAIG MATHIESON