A bonding trip to a forest island turns into a fight for survival for three childhood friends (Katie Aselton, Kate Bosworth and Lake Bell) when they run into a trio of ex-soldiers out on a hunt. At first, the women see no cause for alarm. But a night round the campfire has terrible consequences, leading to a deadly - and horribly one-sided - game of cat-and-mouse. Aselton directs and comes up with the story, but forget all notions of girliness - with dialogue as brutal as the action, Black Rock takes no prisoners.
This is the story of three girlfriends - Sarah (Bosworth), Abby (Aselton) and Lou (Bell) - who reunite for a camping weekend on the Maine island where they spent their childhood holidays.
But if you think it's going to be some sort of touchy-squealy nostalgia trip that only gets spoiled when some nasty boys show up, think again. The hostilities begin before anyone sets foot on Black Rock.
See, after falling out years ago, Abby and Lou now hate each other's guts. But having sneakily got them together, Sarah continues her manipulations with a rather underhanded reminder that life is short.
"We have no idea what's going to happen!" she argues. Like that's a good thing. Still, it gets them on the boat.
Unfortunately, the peace doesn't last long. And any kissing and making up is interrupted by the appearance of three young hunters, one of whom they recognise from their schooldays.
Over supper, they learn that the guys have recently been discharged from the army. Dishonorably. Exactly how dishonorably remains unclear... but they get an inkling when a drunken flirtation gets horrifically out of hand.
The situation rapidly descends into savagery, leaving the girls fleeing for their lives from gun-toting pursuers driven insane by rage.
Unarmed and petrified, they couldn't be more vulnerable if they had to strip naked... Ah.
Brutal in dialogue, performance and deed, this is where Lord of the Flies meets Straw Dogs.
Having starred in the latter (2010 version), Bosworth clearly doesn't mind a fight for survival. Once again, she's the catalyst around which the uncomfortable atmosphere builds.
But it's Aselton and Bell who really impress, their characters providing the glue of credibility that prevents the increasingly overwrought situation from coming apart.
As a thriller that puts the 'grr' in girl power, Black Rock is harder than it looks.