Der Nachtmahr (literally The Nightmare) opens with a warning about extreme strobe lighting and a worrying sounding combo of "isochoric and binaural frequencies," which is followed by the advice that the film should be played loudly. Just a couple of minutes in it makes good on this promise as the teen female trio of Moni, Babs and Tina arrive at a rave and the strobe goes into overdrive and the soundtrack explodes in a gloriously spine-rattling blast of hardcore techno. It's a regular night out for these girls, who dance, hang out and pop a few pills, but when Tina nips outside to take a leak she spies something strange in the bushes and immediately makes moves to head home. Just as she is leaving she spots pieces of her broken necklace lying in the road and when she bends down to retrieve them she is hit full on by a speeding car in a direct replay of a viral video shown to her earlier by one of her friends. When she wakes up she has experienced a brief time rewind and is still at the party recovering from a faint. She and her friends then depart and pre-accident conversations are replayed, but this time Tina stays firmly in the car.

Back home that night she is disturbed by strange sounds coming from somewhere inside of the house, but a plea to her parents to sleep in their downstairs room falls on unsympathetic ears. When the noise starts again she traces it to the kitchen, and what she sees when she opens the door sends her screaming upstairs. The next day a security firm fails to find evidence of a break-in and Tina's parents are convinced she's been having bad dreams. Her psychiatrist is understanding but suggests to Mum and Dad that if things don't improve then it may be time to put their Tina into a clinic.

With her parents away for a couple of days, Tina is left alone in the house and the noise returns, but this time she enters the kitchen and switches on the light. Working its way through the contents of the fridge is a large and smooth skinned homunculus, which pays her no heed and continues its slow investigation of the food that has splashed at its feet. As Tina watches in astonishment, a group of her friends show up at the front door to take advantage of her parents' temporary absence, and Tina leads Mona and Babs into the kitchen to show them the cause of her recent malaise. The food is still on the floor and the fridge door open, but the creature has departed. Tina tries to pass the whole thing off as a joke, but even her closest friends are starting to doubt her sanity now.

For the first third at least, we're in largely familiar horror film territory. Tina is disturbed by noises in the night, is sent screaming by something lurking in the dark, and a creature that only she sees vanishes the moment she asks anyone else to bear witness to its presence. It doesn't take us long to realise that the creature is a product of Tina's anxiety, but it's initially uncertain whether it has physical presence or is the result of viewing events through Tina's troubled and possibly hallucinatory eyes. My growing engagement with Tina and her plight led to me favouring the former from an early stage, a viewpoint encouraged by a scene in which the creature crawls up to the sleeping and unaware Tina and curiously looks her over, something she would have had to be conscious to imagine. When confirmation comes it brings a new set of potentially lethal complications, with any injury inflicted on the creature immediately replicated on Tina, which itself gives rise to some misinterpretation of Tina's behaviour and state of mind.

It soon becomes clear that Der Nachtmahr, the debut feature from German visual artist AKIZ (real name Achim Bornhak), is not a straight-up horror film but an exploration of teenage angst dressed in horror clothing. Once exposed to the light, the creature is certainly a disquieting presence but is never a particularly threatening one, having the quality of a new-born sloth with a dozy curiosity for its immediate surroundings. Like the children of rage in David Cronenberg's The Brood, it's a physical expression of an emotional state, a crawling metaphor that its owner at first fears but later learns to tolerate and over the course of time to emotionally embrace.

Some early reviews have been a little dismissive of the film for offering no new insight into the psychological pain suffered by its central character (funny how you rarely see complaints that love stories never seem to expand our understanding of that particular emotion). They may well have a point, but I'd still argue that AKIZ has chosen to explore this territory in an inventive and oddly arresting manner, and it's been a while since I bonded with a character who felt so utterly and completely isolated from the very people that she should be able to turn to for support. This is vividly expressed in the performance of actor Carolyn Genzkow, who brings a sometimes heart-tugging authenticity to Tina's loneliness and her gradual and seemingly  helpless drift towards despair.

It builds to climactic sequence of (symbolic) exposure of the inner self and an ending that is open to multiple readings, including one so hoary that I'm seriously hoping that this was not the intended interpretation, as for me this would undermine much of what led us to this point and kick against the creativity at work elsewhere (sorry, I can't say more without delivering a serious spoiler). But the film's strong metaphorical element can't help but suggest there is more to the conclusion that first meets the eye, and as someone who had his own share of issues in his teenage years, Tina's very personal journey gave me more to reflect on than the supplied synopsis had led me to expect. It may be not be saying anything particularly profound, but Der Nachtmahr still effectively captures that sense of isolation that so many of us experienced during our teenage years, and does so in an unusual and imaginative way.

I do, however, have one logic question. From an early stage the film goes out of its way to show its teenagers as people who are tied to their smartphones, which they use to text, listen to music, watch videos, you name it. With this in mind, I did wonder why Tina never once put one of her phone's key features to use and try taking a picture or a video of the creature that no-one else believes she has really seen.

The next screening of Der Nachtmahr at the 59th BFI London Film Festival on the following date:

Saturday 10 October 2015 21:00
Hackney Picturehouse, Screen 1

The 59th BFI London Film Festival runs from 7th to 18th October 2015.
For further information on the films being screened and to buy tickets for showings, head here:
https://whatson.bfi.org.uk/lff/Online/