Are you sitting comfortably? Well, that's not going to last.
Writer-director Craig Zobel's relentlessly unnerving study of acquiescent blue collar workers manipulated into inflicting sexual humiliation and worse in the name of co-operation with authority leaves you in a dark moral place you'd really rather not be.
Viewers turn to grubby voyeurs as the degradations are heaped on an innocent fast food worker and the dawning realisation that this sordid story of exploitation is based practically scene-for-scene on a real story leaves you hoping 'only in America.'
This is working class, backwoods USA - specifically Ohio - centring on a greasy diner where stressed-out manageress Sandra (Dowd) receives a phone call from an Officer Daniels (a chilling Pat Healy) during rush hour.
His disembodied voice tells Sandra that one of her staff - perky teenage waitress Becky (Walker) - is suspected of taking money from the purse of one of her customers, a sneaky theft witnessed by his surveillance team.
Sober and persuasive, Daniels not unreasonably asks Sandra to bring Becky to the back of the diner to answer a few questions...and then things get seriously disquieting.
Claiming he's got the authorisation of Sandra's boss and unable to spare any officers to attend the scene, Daniels persuades Sandra carry out a strip search after Becky is terrified into believing it will spare her a trip to the police station.
It gets worse. Daniels - by turns charmingly cajoling and brutally bullying - coerces Sandra into placing a male burger flipper in charge of the near naked teen as the grim scenario develops a sexual angle. And then it get worse still.
This skin-crawlingly lays on the humiliation-by-increment to a bizarre stage when you're convinced it's dramatic licence only to discover that what you're seeing actually happened.
The story is based on a real occurrence at a McDonalds in Mount Washington and was one among 70 similar cases in thirty states across America.
Zobel - helped by fine performances from Dreama Walker as Becky and a stand-out from Ann Dowd as Daniel's malleable stooge - takes an unadorned, sober approach to a situation that was the perfect storm of an arch manipulator exploiting trusting, simple folk to a degree that went beyond the bounds of reason.
This is a movie where you're the silent witness who's desperate to shout.