The camera glides and swoops over some mountains because that looks really cool.
Stock footage of a helicopter on a sonar testing mission off the Alaskan coast. Shaky camera suggests a man in a helicopter pilot's uniform is the pilot of the helicopter.
He'd better be careful where he drops that sonar device...
Enter Deborah Gibson...
Stock footage of underwater research diving vessel thing.
'Deborah Gibson', the '80s pop princess who wasn't as good as Tiffany pretends to be piloting it by holding a joystick and looking into the screen.
She has a great love for the undersea world ("It's pure poetry!")
Stock footage of assorted marine life.
The Beasts Unleashed
"Something's messing up the whale's vibration pattern!" gasps Deborah Gibson.
The camera shakes a lot and the helicopter crashes ("Holy crap!")
Turns out it's dropped a low-frequency sonar device that disturbs some whales who crash into a glacier and awaken two massive prehistoric beasts.
A Japanese oiling rig seems to be doing perfectly fine until a storm descends.
This makes it dark enough for the rubbish giant octopus CGI to show up and wrap tentacles around the platform.
The camera shakes to depict the horror on-board. Close-up of a giant octo-eye staring at the riggers as it destroys them for some reason.
The Whole Tooth
Deborah Gibson pulls a giant shark tooth out of a beached whale.
She argues with a pesky corporate guy from the corporation that funds her research. He fires her. ("Don't love the ocean too much - it doesn't love ya back!")
"There's something big out there," ponders Deborah Gibson. "Really big..."
Flight Of Shark-Death
Stock footage of a model airliner flying comically fast through some cotton-wool clouds.
A guy on-board looks out of the window ("Holy shit!")
The Mega Shark leaps up and chomps the plane but the shots are so brief and blurry and the camera so shaky we could only get a pic of the man's face.
Deborah Gibson takes the giant shark tooth to her wise old Irish professor who, in a very Irish way, calls her 'lassie' a lot.
"The bloody feds," he rages. "They'll hound you until you're leaking from every orifice!" Eww.
Dr Irish-Fella looks into a microscope and proclaims the tooth is from a Megalodon, a prehistoric shark that was made extinct 1.5 million years ago.
"That's impossible!" gasps Deborah Gibson.
Kindly Japanese scientist Dr Shimada hooks up with Dr Irish-Fella and Deborah Gibson.
Dr Shimada shares a comically unlikely lingering gaze with Deborah Gibson who later slips into a lovely low-cut number before they all watch video taken during her undersea voyage.
They all gasp as they see images of a Mega Shark and a Giant Octopus, before having a resigned chat about how humans have exploited the natural world and melted the polar ice-caps and all that.
"Maybe this is our come-uppance..." mopes Deborah Gibson.
A US naval destroyer engages the Mega Shark.
The all-out action is represented with stock footage of a US destroyer firing its guns intercut with shots of men in sailor costumes shouting ("Send that big bastard down!")
A rubbery dorsal fin approaches a toy boat in a bath.
The camera shakes. The shark wins.
Deborah Gibson, Dr Irish-Fella and Dr Shimada are arrested by the government.
Dr Irish-Fella pops out another slightly wrong and icky line ("Twenty years ago my ideas were treated with disdain and discharge!")
Plenty of unnecessary swearing here from a racist government official ("We have to find a way to stop this fucker!")
"What do you want?" asks Deborah Gibson. "Solutions!" he confirms.
They all discuss how to trap the mega-creatures.
If only something would incidentally happen that could give them an idea how...
The trio pour some coloured liquids into other coloured liquids.
They shake their heads a lot to depict disappointment.
Dr Shimada and Deborah Gibson kiss and enjoy an unconvincing sex scene in a store cupboard.
In the afterglow, they talk about how scent is a big attractor. Deborah Gibson has a eureka moment... ("Pheremones!")
The plan is to lure the megabeasts to separate bays using special monster perfume and then, er, trap them in some way...
A reconnaisance plane flies too low and is whipped and exploded by the Giant Octopus.
"Noooooooooooooooooooo!" screams the pilot with remarkable foresight just before the plane is hit.
Everyone shakes their heads and looks down to depict shock and horror.
Gapping The Bridge
In San Francisco, Deborah Gibson and Dr Irish-Fella lay some pheremone bait for the Mega Shark.
But it leaps up and bites the Golden Gate Bridge in half, killing hundreds of people.
The watching racist government official shakes his head sadly to depict shock and horror.
In a protracted finale of shaky cameras, the Mega Shark and Giant Octopus are drawn together off the Alaskan coast, have a big fight (with lots of squelching) and kill each other.
"What's happening?" someone shouts. "It's impossible to tell!" a colleague observes.
Indeed it is - because the CGI is so poor they have to keep the lighting really low.
"Looks like they finally finished what they started 18 million years ago!" notes Dr Irish-Fella as the Giant Octopus strangles the Mega Shark which somehow manages to kill the Giant Octopus just before it dies.
Later, Deborah Gibson and Dr Shimada ponder their future on a beach.
They plan to visit the North Sea where reports suggest the presence of a plot idea that could lead to an unnecessary sequel.
That's it. All the best bits were in the trailer and we'll never have those precious 90-odd minutes of life back.
But at least you only had to spend three or four minutes reading this feature to learn that Mega Shark vs Giant Octopus is total and complete cock.
A third of a star. For the Golden Gate Bridge bit.