Directed by Jorge Michel Grau. Starring Paulina Gaitan, Daniel Giménez Cacho 16 cert, Cineworld/IFI/Light House, Dublin, 90 min

A PLAINLY deranged man wanders around a shopping centre until his gaze fixes on two scantily attired store mannequins. He points at the plastic, vomits something dark and ominous, and drops down dead. Diligent cleaners tidy away the ensuing mess in a matter of minutes.

The man’s surviving family members are distraught. Dad may have had a weakness for “his whores”, but he could be relied upon to put meat on the table. His untimely demise means that one of the brood will have to assume certain responsibilities. But which of the grown children – sensitive Alfredo, sensible Sabina or sociopathic Julián – has the capacity to scour the underpasses of Mexico City for the family’s human victims?

It seems unreasonable to complain that this new South American cannibal horror film doesn’t always make sense, but Jorge Michel Grau’s directorial debut is a wayward, secretive sort of movie. We’re never quite sure why the clan has taken to human flesh, nor can we decipher the meaning of their bizarre sacrificial rituals. We do know, however, that this folie à plusieurs is all that keeps them together.

Forget the extreme cooking: the heart of We Are What We Areis this queasy distinction between unacceptable behaviours and domesticity. "We're monsters," announces the family matriarch as she and her children drive long with the body of a mutilated streetwalker in their boot.

They are, in fact, probably no worse than anyone else in the nasty Darwinian slums they call home.

As Grau’s focus shifts from the dysfunctional family unit to the dysfunctional society, we come to see that everything in this picture is rotten. The people are disheveled, the homestead decaying, the streets rife with corruption. “What are we paying you for?” prostitutes rage at bent cops. Elsewhere, morgue workers ponder how the vogue for cannibalism might be turned into profit. Tellingly, the film is set in the writer-director’s childhood neighbourhood.

With knowing nods toward Todd Browning's Freaksand a conceit that goes back to Jonathan Swift, We Are What We Arerevels in the grotesquerie of poverty. Best skip dinner.