In this full foray into alternate universes, The Magicians drops Josh and Julia directly into the twenty-third timeline: the universe where the one living Alice remained. Initially contacted by alternate Josh, they're told that the other universe is in dire need of help. But once Josh and Julia arrive, they realize it's a trap set by alternate Josh and an alternate (and very alive) Marina to give the Beast what he wants. After a display of her god-like magic powers, Julia manages to convince Josh (2) and Marina to help her stop The Beast and get the key from him.
The journey leads them to a library, where they discover how alternate Eliot and Margo died before Julia grabs the spell off their dead bodies that Alice used to kill the Beast in their timeline. On the way out, she and Marina bump into an alternate version of Penny who upon seeing Julia, kisses her. She learns that in his timeline, he and Julia were soulmates. After explaining how things are different in her own timeline, Penny agrees to tag along to help stop the Beast.
Once they converge back on Marina and Josh's headquarters, Julia has minutes to practice before the Beast shows up. But the expected Martin Chatwin isn't there. In his place is a shade-less Quentin eager to kill them all. After Julia and Penny team up to use her magic and his traveling powers, they manage to get away but use that time to craft a plan to take him down that involves Alice. After finding her on a Fillory boat full of rabbits (she's radish smuggling for them), Alice reveals her role in bringing Quentin back and the weapon that can stop him.
The team jets to Quentin's Chatwin fanboy hangout in an attempt to bring him down. It's less a fight and more a failed sneak attack, which sees Alice die and Julie force her shade into Quentin. After he comes face-to-face with what he's done, Quentin kills himself but not before revealing the next key's vision of the future. In it, Julia unlocks not magic but a monster more frightening than the Beast.