Meg 2: The Trench sees Jason Statham and Cliff Curtis once again wrestling with giant, prehistoric sharks at the bottom of the Mariana Trench.
The original Meg was a Chinese-American co-production, mostly shot around New Zealand, about Jason Statham taking on a gigantic prehistoric shark - a megalodon.
He was given able assistance from Kiwi star Cliff Curtis, Chinese celebrity Bingbing Li and a cute little Chinese moppet called Sophia Cai.
Cliff and Sophia return with the Stath, though both New Zealand and Bingbing Li are abandoned before Meg 2: The Trench.
"The Trench" being the famous Mariana Trench, the deepest part of the ocean anywhere, and the home of the last movie's invading megalodons.
For the second film, director Ben Wheatley decides we need an historical recap. Flashback 65 million years…
A caption explains that the world was inhabited by dinosaurs of all shapes and sizes, but the king of them all was…. Anyone? That's right Tyrannosaurus - "T" to his friends - Rex…
But was it really? What's that hurtling in from the sea, and aiming at our carnivorous friend? It's a big, galumphing mega-shark - rather poorly animated, it has to be said.
Okay, that's all the explanation this story needs, thinks director Wheatley, who's better known for rather more intellectually rigorous art-films like A Field in England, High Rise and Happy New Year Colin Burstead.
Wheatley immediately throws us into the middle of some problems in the Mariana Trench.
Jonas (Jason Statham) is now an eco-warrior taking on ratbags who dump nuclear waste in our oceans. Don't worry about that.
He's also inherited the late Bingbing Li's daughter Meiying - now a stroppy teen - as well as Meiying's heroic Uncle Jimmy, whose hobby is training a tame megalodon. That's not important either. Cliff Curtis, tell us what is…
There have been people - possibly nuclear ratbags - tampering with the Trench, and once you start doing that, who knows what you're going to unearth?
Jonas and his buddies decide to take a couple of deep-diving minisubs down into the deeps to find out what's up and who's doing it. No, not you Meiying…
But of course we know that saying no to a stroppy teen is a waste of time in this sort of movie.
Meg 2: The Trench is firmly aimed at a family audience, much to Jason Statham's disapproval, I gather. This means not much swearing, but plenty of enthusiastic - if bloodless - violence. And it also means that Meiying gets to stow away on the sub.
OK, so far so good. Once we get down to 25,000 feet or so, it's anybody's guess what we're likely to find down there.
Is it really? Well, no, not really. Because we've all been waiting for the moment when we're attacked by bigger and better megs.
You may be wondering what actually stirred up our giant finny friends, and it has to be admitted that about here the plot becomes a little murky.
In fact, the trailer is rather more helpful at explaining what's going on than the actual movie.
It turns out there are bad guys on the loose in the Trench, as well as megs. They've been mining valuable minerals down there, minerals they discovered were ripe for the picking.
How did they discover that, you may ask? Look out, what's that behind you? Stop asking questions and run for your life!
Meanwhile we've got to keep an eye on a few of Cliff Curtis's associates topside, some of whom may or may not be in league with the bad guys, whoever they are.
In fact every time I wondered what exactly was going on, in terms of any sort of plot, there'd be another attack from giant prehistoric sharks - including Uncle Jimmy's pet one, that got away while we weren't watching.
The plot struggles to even count as "incoherent", as we blunder about on the ocean bottom, then into a hitherto unknown undersea station full of villains, then suddenly topside - has no-one heard of the dreaded bends? - where a holiday resort full of honeymoon couples finds itself under siege by megs attacking in formation.
I know, Heart's Eighties hit "Barracuda" seems to be putting it mildly, and you won't be surprised to learn that this noisy, pig's breakfast of a movie hasn't exactly proved a favourite with the critics.
Even by Jason Statham's usual standards, Meg 2: The Trench fails on every level.
But wait, what's that sound as the final credits roll?
It was the sound of spontaneous applause from my audience, and as the lights went up I could see why. They were mostly kids, delighted that the film's PG rating meant they could enjoy the sight of monstrous sharks attacking Jason Statham.
They loved it and couldn't care less that it made no dramatic sense whatsoever. Did it have gigantic sharks? Yes it did. Did it have a few jokes - including a call back to that cute little doggie from the first Meg? Absolutely.
And has it encouraged them to see more - possibly far better - movies at a cinema next time?
Certainly it has. And for that reason alone, I'm not going to get too snooty about Meg 2: The Trench.
