Subaru & co heads to a lake city to negotiate a deal with the mayor. He has a precious stone that Emilia can use to bring back Puck from his sleep. (the gem that housed Puck was destroyed in arc 3 or 4, I can't remember)
All five of the queen candidates gather in the city for... I can't remember why, but I believe Anastasia summoned them.
But this posed a serious national security, having all of them at one spot... and of course, the Witch Cult arrive to terrorize the city. One of the things they were looking for was a copy of the Book of Wizdom that belonged to Roswaal and now in Subaru's team's possession.
Anyways the whole arc becomes a massive war between the Witch Cult vs everyone we've been introduced to so far.
Team Emilia:
Subaru & Betty, Otto, and Garfiel
Team Cruch:
Wilhelm, Felix
Team Anastasia:
Julius, The cat triplets, Ricardo and his mercenaries
Team Felt:
Reinhart, Rom, the three thugs Ton/Chin/Kan
Team Priscilla:
Al
There are several incredibly strong powerhouses on Subaru's side, but they're still mostly in massive disadvantage (with the exception of Reinhart, but he can't be everywhere at the same time..) because FOUR Bishops leads this terror attack.
Remember, just a single Bishop caused so much trouble and misery in arc 3. Here we have four of them, and they're all hax as hell.
Just like Betelgeuse, each of the Bishops have horrifying abilities straight out of horror films. I'll get into that in another post.