[This is a review of Teen Wolf season 3, episode 18. It contains SPOILERS.]

Nightfall in Beacon Hills hasn’t proven to be a very peaceful time; it might have something to do with all the werewolves and demons running around. The night in which ‘Riddled’ takes place is no exception, as Scott’s evening begins with a phone call from his best friend, Stiles, who has apparently sleepwalked his way into an industrial basement and been accosted by a bear trap.

With the temperature falling and Stiles already suffering the first signs of hypothermia, the race is on to find him before he freezes to death and just about every character on the show pitches in with the search. One of the most useful participants is Lydia, whose gradually emerging banshee powers have turned her into a kind of psychic sniffer dog for trouble and strife, both of which can be found in abundance in this episode.

‘Riddled’ also features a threat that is a lot less supernatural than the nogitsune and a lot closer to home for many viewers: terminal illness. As hinted in last week’s episode, Stiles is beginning to display early symptoms of frontotemporal dementia, the degenerative disease that killed his mother, for which there is currently no cure. Because the dementia and the nogitsune possession have symptoms in common – such as confusion, insomnia and blackouts – it’s difficult to tell whether the two conditions are connected or whether Stiles is just really, really, really unlucky.

Juggling a possession double-act and a storyline involving terminal illness is no mean feat, and with a lesser actor leading it ‘Riddled’ might have collapsed into cheesiness. Dylan O’Brien, however, has been steadily emerging as the strongest young  talent in the show and pushing Stiles to center stage has definitely been of benefit to this half of the season, even if it means that the werewolf elements of Teen Wolf have been somewhat sidelined.

‘Riddled’ isn’t without its flaws; having a character converse with a darker version of themselves was already clichéd by the time Lord of the Rings did it and the writers probably could have gone with a better monster than a bandage-wrapped demon with a Bane voice. The Gollum comparisons aren’t exactly assuaged by the fact that Stiles’ other half wants to play a game of riddles in the dark, and as such the surprise reveal at the end of the episode isn’t much of a surprise.

Much of Teen Wolf – this season in particular – has been built around a set of visual motifs, with each episode introducing a strong symbol or image. In ‘Riddled’ the setpiece is Stiles’ crime collage project, another element that was foreshadowed in a previous episode, which has now blossomed into a kind of art installation with the red strings of unsolved cases all connected to a pair of scissors stabbed point-down into his bed. Needless to say, it’s a bit unsettling.

There are a few sub-plots that get some time to circulate in this episode, one of which involves the reasons behind Derek Hale’s return and his offer of aid. Perhaps in an effort to keep at least a bit of wolfiness in Teen Wolf, ‘Riddled’ sees Derek and Scott finding some common ground in their frequently adversarial relationship, as Derek offers to play Obi Wan Kenobi to Scott’s Anakin Skywalker and teach him the werewolf trade secrets that he’ll need to protect Beacon Hills. Hopefully Scott won’t turn evil during his training; there’s quite enough of that going around.

‘Riddled’ is a powerful episode, but it also sets up plenty of story threads that are going to be challenging to wrap up in the few episodes that are left. The stakes involved certainly beg the question of just how far this arc might go – could season three end with a character death?

Teen Wolf returns next Monday with ‘Letharia Vulpina’ on MTV @10pm. Watch the promo below.