He said he’d be back, and sure enough Arnold Schwarzenegger returns to the franchise that made his name for this convoluted and confounding exercise in everything-and-the-kitchen-sink filmmaking.

James Cameron may not be everyone’s favourite director, but in The Terminator (1984) and its game-changing sequel Terminator 2: Judgment Day (1991) he kept the narratives straightforward, the characters interesting and the action eye-popping.

Cameron was smart enough to avoid getting bogged down by the head-scratching ins and outs of time travel; instead using it as a device to drive the action rather than the other way around.

Alas, the same cannot be said of Terminator Genisys, which ignores the events of Rise Of The Machines (2003) and Terminator Salvation (2009) – no bad thing – and instead tries to have its cake and eat it by invoking Cameron’s first two installments whilst rebooting the franchise.

It’s a tactic that is becoming increasingly popular in Hollywood following the success of J.J. Abrams’ Star Trek (2009), which cleverly took the Trek franchise down an alternate timeline whilst still keeping everything that made the series so successful in the first place.

Here, director Alan Taylor (Thor: The Dark World) faced an uphill task from the word go, working from a nonsensical script by Shutter Island scribe Laeta Kalogridis and Patrick Lussier, whose most recent credit is, er, Drive Angry, and delivering a movie that has the whiff of studio interference all over it.

The messy trailers didn’t exactly sell the film and a later trailer (not the one I’ve linked to in my review) stupidly gave away a crucial plot twist – a sign that usually signals a studio’s lack of belief in a product.

Genisys follows resistance fighter Kyle Reese (Jai Courtney), who is sent from a 2029 ravaged by Skynet’s apocalyptic destruction back to 1984 by leader John Connor (Jason Clarke) to protect his mother Sarah (Emilia Clarke – no relation) from a Terminator, or Terminators as it turns out. However, Kyle gets a shock when it emerges that Sarah isn’t the defenceless waitress he’s been expecting, but rather a kick-ass soldier who has been protected from childhood by a reprogrammed T-800 model Terminator (Schwarzenegger).

That just about covers the first 20-30 minutes, which actually promises much before the shark gets truly jumped over and the time travel-laden plot goes off the deep end.

The method behind Skynet’s ploy to achieve world domination is at least relevant to the digital age, but by treading over Cameron’s original the film ties itself up in a ridiculous amount of plot threads to get to where it needs to; with lazy waffle about time nexuses and dual realities served up as creaky bridging points to keep the whole thing from crashing and burning (and failing in the process).

Whilst the script goes off in a multitude of head-scratching tangents, the film attempts to divert the audience’s attention away from picking black hole-sized holes in the plot (who sent Arnie back to protect a young Sarah? Actually, who cares) by piling in action set piece after action set piece. Machines that Cameron’s movies built up to be near unstoppable killers are disposed of with relative ease early doors to make way for the central villain, whose identity is the film’s supposed ace card but only serves to undermine the first two, far superior, installments.

Arnie is clearly having a good time as everyone’s favourite cyborg. Although the explanation for an ageing Terminator isn’t entirely convincing, it does allow him to point out to all the haters that he is “old, not obsolete”. Emilia Clarke is given a rather thankless task in an underwritten role and the chemistry she shares with a very average Courtney is, at best, tepid.

Jason Clarke, meanwhile, looks like he’s treading water waiting for the next Apes picture, while JK Simmons gets to loosen up in a fun role as a police officer who’s lucky to be alive and Matt Smith, like so many others, gets virtually nothing to do.

This is the start of a supposed trilogy – on the basis of Terminator Genisys, Judgement Day can’t come soon enough.