We know what you're thinking: not another serial killer movie. On paper, it's worse than that: it's yet another serial killer movie about a serial killer who hunts serial killers. See Dexter, Repairman Jack, et al. Happily, Billy O'Brien, the Irish director behind the underrated rural horror Isolation (2006), has fashioned a sour, wicked film that neither looks nor feels like the rest of the busy sub-genre.

John Wayne Cleaver (Where the Wild Things Are's Max Records) is a small-town Minnesota teenager whose love of mass murderers has convinced him, but not his psychologist, that he is, in fact, a serial killer in waiting.

A social outcast, John’s obsession is not helped by the fact that his mother April (Laura Fraser) owns a funeral home, where, of late, strangely mutilated bodies have been arriving. Intrigued and ready to sleuth, John gets on the case and fixes on Mr Crowley (Christopher Lloyd), an elderly neighbour, as his prime suspect.

He soon starts helping the old man and his wife around the house, hoping to prove that Crowley is not as jolly or feeble as he seems to be. The truth, when it is revealed, is far weirder than anything John’s admittedly over-active imagination might have come up with.

A muffled tone, not unlike George Romero's Martin, and an initially slow-burning drama finally tips into a gloopy final stand-off between Records and Lloyd. Back to the Future diehards might want to look away: three seasons of Rick and Morty may not have altered your perception of Doc Brown, but I Am a Serial Killer is a game-changer.

Award-winning cinematographer Robbie Ryan finds interestingly grubby things to do with snow and darkness for this pleasingly unusual chiller.