On Teen Wolf Season 5 Episode 20, it's time to take down Sebastien. Everyone's got a different angle. The Argents are working with Parrish. They have the The Maid of Gevaudan's pike. Their game plan is to lure the Beast to the fight. Of course, this fight happens in the sewers.
Sebastien stops by the Sheriff's station before heading down to the sewers. Unfortunately, he claws Lydia's throats and brutally wounds Hayden in the process. Deaton believes that if Lydia says the Beasts' true name (Mason) that Mason will be brought back to us. This is a little difficult since Lydia's voice is basically gone, but thankfully there's cortisone shots for that.
Theo's still focusing on the absorbing everyone's power to make himself strong enough to take on the Beast. His latest victim is Tracey. Then, he tries to kill Scott, but when he goes up against the Beast, it doesn't work. It turns out that Deucalion has been working with Scott all along. Oh, and he's not blind. Unfortunately, Deucalion only broke Theo's neck, and Theo isn't dead.
Yup, Deucalion and Scott have been working together all along, as have Argent and Scott. Second double cross alert! Argent knew that Gerard wasn't helping to save lives, he was helping to make himself immortal. Argent gives Scott and Liam the pike, and it's a gun stare down with Gerard. Someone fires.
Kira rescues Lydia who was trapped in some random room in the sewer. Now, Liam and Scott are fighting against Sebastien and losing. Sebastien has his claws in Scott's neck when he sees her - Allison. It shakes him up enough that Scott is able to break free, giving Lydia time to say Mason's name. Mason is back, and Parrish and Scott kill whatever's left of the Beast.
Oh, and Kira uses her sword on Theo. The ground splits open and Theo's sister drags him to hell. Yup, it happened.
Meanwhile, Malia fights her mom, and ends up using the glowing blue talons on her to steal her power. Sadly, it's unlikely that the Desert Wolf actually died.
We end with Kira going off with the skin walkers, the Sheriff welcoming Stiles to his future in law enforcement, and a great shot of Lydia, Scott, and Stiles in the library. Until next season, Teen Wolf.