This movie makes it really clear that director Ralf Kemper is a big fan of the '80s slasher genre. It's got a lot of the common horror tropes, but it also adds some different technological twists and honest to god terrifying scenes that I really wasn't expecting.
Basically, this group of people go into the woods, find an abandoned bunker, and suprise! There's a demon in there that wants to possess them (I didn't tag this spoilers bc the movie is literally called "Possession").
This is a foreign made film-the actors are all German, but they all speak English. For the most part they are pretty easy to understand but there are a couple bits that I would have appreciated subtitles.
Save for a few scenes that will legitimately give me nightmares, this movie was a lot of fun and I don't regret watching it.