On The Magicians Season 4 Episode 12, The Monster has taken Julia and plans to use her body as the vessel for his sister.
Meanwhile, Margo, Penny, Alice, and Quentin are trying to figure out how to potentially save Julia from The Monster. While they likely have everything they also need twice as much magic so that they can take them both down. Fortunately, Fen and Josh found a reservoir of magic. The problem is, the reservoir is cursed and turns anyone who touches it into a fish. Including Josh.
Fen brings the fish Josh back to Earth and explains that Josh is a Fillorian Dying Fish who needs constant eye contact to stay alive. Fen was maintaining eye contact but Josh has bonded with Margo. So Margo continues to stare at the fish and look for cures.
In The Library, Kady and Zelda have big problems. Their bug protection has worn off and they are facing death. However, Christopher Plover is there and he thinks he has a way to help them stay alive, which turns out to be useless when he remembers an age suspension spell Martin Chatwin cast on him.
Not all hope is lost, because Dean Fogg has a plan to break Zelda and Kady out. It's a good thing that he wore his new suit.