Warning: This review discusses the movie’s plot.

Following the death of her mother, Blake Lively’s aquiline medic, that director Jaume Collet-Serra rightly imagined would look great in a bikini, and whom he goes on to ogle for most of the movie, seeks out a beach in a tropical paradise that meant something to her dear departed. She subsequently gets a harsh lesson about trading on your parents’ memories instead of creating your own, when she’s attacked by a Great White Shark. Retreating to a mini-island, many hundreds of yards from safety, she’s left to improvise a game plan before the tide takes her sanctuary and reunites her with the circling snapper.

That’s just about all there is to The Shallows; it’s a high concept, one scenario shark movie, with a lone dull protagonist. Movies about one person against the elements can work very well of course; Cast Away did the business for Tom Hanks, All is Lost managed to grip thanks to a stoic, near silent performance from Robert Redford, and audiences cheered while James Franco hacked off his own arm in 127 Hours, but there’s less to The Shallows than all those offerings. For one, where there’s contrivance it’s a great deal more conspicuous, and for another, Lively just doesn’t have the magnetism to carry the movie alone. Rather the screenplay, which never quite manages to flesh out the horrifying possibilities of the premise, underwrites the character – having her either talk to herself in unconvincing expository snippets, or trade heart warming dialogue with the wounded seagull on her rock.

If there was any doubt that Collet-Serra knew of the script’s limitations, it’s confirmed when we note how he’s beautified the photography and distended the thing using empty stylisation in a bid to enliven Lively’s ordeal. Spielberg didn’t shoot Jaws (yes, comparisons are inevitable) like a deodorant commercial because he was making a grounded thriller, mindful of Hitchcockian technique. That, and he wasn’t yet privy to 21st century advertising.

Collet-Serra’s film is a one dimensional affair that starts with its central tussle and works backwards, equipping its heroine with all the necessary skills and lucky breaks she requires to defeat her foe. If you’re bitten in the water, you’ll want to be an experienced swimmer and surfer with a medical degree and jewellery you can repurpose as makeshift stitching. It also helps if the shark’s later victims had a helmet mounted Go-Pro camera that washes up close by, allowing you to record a help message that will eventually alert those on land to your predicament. But to be fair to Collet-Serra, the manner in which the shark’s defeated is so extraordinary and such a staggering piece of improvisation on Lively’s part – I’m not sure any form of words would do it justice – that no audience member could see it coming. That’s right, no compressed air or trawled up power cable here. Why seed the solution when you can pull it right out of the movie’s rear orifice? The Shallows is shallow indeed.