[This review of Teen Wolf season 4, episode 9 contains SPOILERS.]

-

This week, Teen Wolf finds yet another excuse to have a series of scenes at a party (presumably as an excuse to shoehorn in more of the latest pop music tracks) so 'Perishable' - with its heartfelt tale of love, murder and intrigue - is set to the soothing tunes of "Bootie in Your Face", "Rave Life" and "Twerk". The party music is so headache-inducing, in fact, that it eventually turns out to be a complex method of assassination being used against Scott, Malia and Liam. What an awful way to die.

'Perishable' also introduces season 4's version of season 3's Japanese concentration camp from 'The Fox and the Wolf': another random piece of historical backstory that is thrown in more or less out of nowhere. This time it's Lydia's grandmother, Lorraine, who had a love affair with a woman called Maddy that was brought to a tragic end when Maddy decided to take a boat out into a storm (for laughs?) and was horribly drowned. The story would probably be more tragic if more than a couple of minutes was spent dwelling on it. It's also narrated somewhat oddly, with Lydia taking the lead and other members of the group chiming in with advance knowledge of what happened next. Did they rehearse beforehand?

Before the wild party and the random flashbacks roll in, however, the episode kicks off with a new development in the Deputy Parrish mystery. The ambiguously supernatural police officer finds himself targeted by one of his colleagues, who intends to barbecue him inside a police cruiser and collect the reward for his assassination. Parrish, however, escapes the flames completely unharmed. Is he a... werephoenix?

One of the more distracting elements in 'Perishable' is the plot hole dragging along behind one of the major plot points in the episode. When trying to figure out the cypher word needed to unlock the code left behind by her grandmother, Lydia explains that she used to be obsessed with "The Little Mermaid" - specifically the Hans Christian Andersen fairy tale and not the Disney movie - after reading it with her grandmother every night. She was so obsessed with Andersen's fairy tale, in fact, that she insisted everyone call her Ariel (this, of course, turns out to be the cypher word).

One problem: the little mermaid wasn't called Ariel in Andersen's story. That name was invented for the Disney movie. If the writers wanted to get credit for a literary reference, it would have been prudent to actually read the 9000-word story first (#readingisfundamental). It might seem like a minor detail, and perhaps it could be explained away with a bit of mental stretching, but it indicates a real lack of attention to detail that seems to extend into Teen Wolf's overall slapdash plotting and dangling story threads.

Speaking of which, Derek reveals to Scott that he has lost all of his werewolf powers, but still doesn't seem to be particularly bothered by the fact. In fact, a lot of Derek's reactions have been pretty flat this season - though whether that's an acting issue, a writing issue, a directing issue, or whether Derek has simply started taking Prozac is difficult to determine. If Derek does end up dying this season, as he himself predicts in casual tones, he'll probably die with a mildly disappointed expression on his face.

Danny Mason at least gets something to do in this episode besides casually bring up the fact that he's gay in every conversation, ultimately saving the day by turning off the music that is crippling Scott and the other supernaturals at the party. Hopefully this is the start of a more complex character arc for him, though it's equally possible that he'll return to maintaining his single character trait ("Did I mention that I like guys?") for the rest of the season.

After Stiles and Lydia get locked up by the sadistic Eichen House warden from the last season (who turns out to be properly evil and not just abuse-of-authority evil), the big Benefactor reveal happens and it turns out that the creator of the deadpool is... Meredith. This would probably have been more shocking if Beacon Hills' cemetery did not have a revolving door.

Teen Wolf returns on Sunday with ‘Monstrous′ @6PM on MTV. Watch the promo below.