Films based on video games rarely, if ever, work out – horror films based on video games particularly so. Releases so far range from the painfully mediocre (Silent Hill, the Resident Evil franchise) to the downright atrocious (the many abominations of Uwe Boll). Given this, you would be within your rights to approach John Hsu’s adaptation of Detention with a certain amount of trepidation.

Thankfully, this trepidation is quickly dismissed as it soon becomes apparent this a video game adaptation both ambitious and classy, if flawed; a work with something to say. That something is an insight into a little known (in the West anyway) part of Taiwanese history from the late-40s onwards referred to as the White Terror. A period of martial law where citizens found with books of Communist or leftist thought could be jailed or even executed.

Hsu tells the story of the period through the lens of Fang Ray-Shin (Gingle Wang) and Wei Chong-Ting (Jing-Hua Tseng). Both study the same high school. Both are connected by Mr. Chang (Meng-Po Fu) as he is counselling the former, and the latter is part of a secret book club set up by him. To give too much more away about how their paths collide and the results would spoil things as the less you know, the better. Suffice it to say this being a horror film it is not nice, that is for sure.

Make no mistake, this is very much a horror film, even if the plot summary does not make it sound that way. And not quite the slow-burn you may expect either. We actually dive into the horror element relatively quickly with the bulk of the scares taking place in a nightmare vision of the school. Whether these are Wei’s actual nightmares is up for debate. Here we follow Wei and Fang as they make their way through eerily empty hallways riddled with monsters and supernatural goings-on. The scenes in this place have a surreal dream logic and, in the best possible way, show its survival horror game origins – as you feel you are going along spine-chilling corridors with the characters.

The rest of the story is told in flashback in the real world. Given this toing-and-froing between the two, it is, initially at least, difficult to get to grips with what is actually happening. Also, there is a general sense of overstuffed-ness here. The film is a tale of political oppression, a love story, a psychological supernatural horror, and a monster movie all wrapped up in one. And it certainly does some of these things better than others.

In terms of horror, it is short, sharp supernatural shocks that hit home hardest. Particularly some wonderfully executed jumps early on. Adding to the unease is the sense of dread Hsu expertly crafts in the “otherworld” version of the school. These scenes bringing to mind the nightmare-scapes of Jacob’s Ladder, a film to which it bears some resemblance. Less successful is the CGI monster element, which, while effective at times, can come over a little on the hokey side. Metaphorically the monsters are a little on the heavy-handed side too.

The real-world stuff is similarly mixed as a film about political resistance and how normal people can become complicit in a system of oppression. This aspect is both searing and captivating. However, the love story element feels less fully realised despite its vital plot function, and while the central three characters are wonderfully realised and acted, most of the other characters are rather thinly sketched.

Despite these flaws, Detention is undoubtedly a powerful piece of horror cinema. Equal parts moving and chilling. It is also likely to be talked about as one of the horrors of the year.

Screening as part of Fantasia Festival