Woman vs. maneater.

Imagine if Chrissie from Jaws hadn’t been eaten in the opening scene and had instead climbed onto the nearby buoy and done whatever it took to survive.

That pretty much sums up what to expect from The Shallows, in which Blake Lively wages a one-woman war against a Great White shark after she’s chomped whilst surfing off a secluded beach in Mexico (in reality Lord Howe Island).

Attacked only a few hundred yards from the shore, Mrs. Ryan Reynolds finds herself in a dead pool – a whale carcass in the vicinity means the shark won’t be leaving anytime soon, and with high tide approaching, the rocky sanctuary she’s managed to reach will soon be underwater. The possibility of a rescue is quickly dashed when a pair of fellow surfers are taken by the shark, leaving her stranded with only a wounded seagull for company (which becomes a supporting character of sorts).

Most of us would be in full panic mode by now, but Lively is a resourceful type, using her med school skills and earrings to seal the bite wound, and fashioning a pressure bandage from her wetsuit. She also times the circling shark to estimate the right moment to swim for her life.

How she manages to stay beyond the reach of this hungry predator makes for a simple and efficient survival thriller that’s slickly shot, including some pop-up graphics for Face Time and to indicate that the clock is ticking. There’s also a creepy swim through a school of stinging jellyfish, and the CGI shark is mostly convincing.

Some of it is implausible, particularly the climax, but the film works so effectively, you’ll quickly forgive the odd lapse in logic. Just sit back, enjoy the ride, and be thankful this isn’t happening to you.

Decent shark movies are a rarity these days, and The Shallows reminds us that a Great White can still be scary in a post-Sharknado world.

In cinemas: August 18, 2016star-3-half
Starring: Blake Lively, Óscar Jaenada, Angelo Jose
Directed by: Juame Collet-Serra