First of all, I loved the end with Mrs. Paddick Morgan and Wong saying goodbye. Two of the series most brilliant writer (Squeeze and its sequel Tooms, Beyond the Sea, Little Green Men) leaving the show for their own show, which gets canceled and makes them come back in the series' fourth installment. And they're leaving with yet another stylish episode.
The first episode to touch dark things like witches, Satan, cult, sacrifices. It gave me the creeps. Mrs. Paddick is an amazing villain, one of the series' scariest so far and can compete with Pfaster of the previous episode and Eugene Tooms.
It was what a monster-of-the-week should be, clever, intense and engrossing and season 2 mostly managed to accomplished that, while season 1 had several cracks in the genre.
Overall, a very strong episode of a very strong season. A wild ride. 9.4/10.