I'm not particularly well-versed in horror films, but a lifetime of cultural osmosis has left me with a good understanding of how it's supposed to go. Morally bankrupt, personality-lacking, or otherwise Orange County everydude Americans are put somewhere dark and isolated through contrived circumstance, and are summarily killed - by a supernatural entity, a guy with a chainsaw, or just 'cause.
Aside from the killings, Demons Never Die entirely ignores this framework - and really it's worse off for it. While I doubt it's a full explanation for why this is the case, Demons is a British film, an oddity in a genre seemingly dominated by the US. Set in London, it has that same mixture of authenticity and self-parody that Attack the Block had with its council-estate setting. The soundtrack is Grime and D'n'B throughout, which I honestly quite liked.
The plot follows a group of kids who form a suicide pact when a girl at their 6th Form College takes her own life. Most have the details as to why they want to die fleshed out, and some are surprisingly serious - the female lead Samantha (Emma Rigby) suffering from schizophrenia, and Ricky (Femi Oyeniran) being pressured by his homophobic father. Lead character Archie (Robert Sheehan) has some trappings of unhinged stalker to his personality, which is interesting in his interactions with Samantha, but after a while it's played as endearing. Odd.
As the story progresses, they eventually realise that an elaborate suicide is not the solution to their problems, and become all a bit more comfortable with themselves. The cast have had their share of movies prior (sharing a few names with Adulthood), and they manage to get some compelling character interaction going, and you find yourself rooting for them to find a solution. That's not how slasher films are supposed to go at all! All of the Final Destinations and the Halloweens out there have almost intentionally flat or dislikeable characters, so when the flesh-rending eventually occurs, we don't feel like awful human beings for finding it entertaining.
Speaking of flesh-rending, that aspect is the weakest part of Demons Never Die by far. At the same time as the suicide pact plot, we find that there is a masked killer picking off the kids one-by-one with a hunting knife. It's clear that the film was produced on a low budget - not being able to go all-out on the violence is understandable, but Demons employs some incredibly obvious cutaways, torn clothing and blood packs; and it feels cheap; especially since the death of the kids doesn't seem to drive the plot as much as you think it would.
Up until the third act where literally every named character ends up knifed (to no real emotional impact - even with all the effort they put into characterisation), nothing would be particularly lost if all the murder scenes were removed. In fact, with some editing, Demons Never Die would be better off as a one-shot BBC human drama.
Part of me wonders if when this film was initially pitched, they had to crowbar in a crazed killer to get it to fit into a Halloween season release; but that's just wishful thinking on my part. There's nothing wrong with having a different take on a genre, but Demons is too tame to be a horror, and too shallow to be a drama – a failed experiment.