As part of an ancient ritual all first year students have to donate a much loved item and Milly is forced to donate Tabby, the one thing that appears to be holding her together. Enid, an old friend from Cackle's, arrives (she looks different!) and reveals she has been kicked out of her college. She pleads with Milly to go with her and travel the world. Milly, faced with separation from Tabby and desperately unhappy warms to the idea. Will Milly leave Weirdsister and her troubles behind for good?
Thunderblast is explaining to Milly about the Great Magic Wheel – symbol of the journey through life and Circle of witches, wise woman, and crones. At the end of every witch's Foundation Year, they have to give up something which is precious to them to join the Circle. Milly has brought Dessie the dragon with her as her offering. The Wheel does not accept it – Dessie isn't a big enough sacrifice. She has to find an offering before the Summer Solstice or she will have to do her first year all over again.
In the dorm room, Milly and Cas are discussing how unfair it is that the wizards don't have to give up anything. Milly realises that she will have to give away Tabby; the thing that is closest to her heart, but she doesn't want to. In the café, Ben is attempting some card tricks with Tim and Azmat. He's not very successful first time, but is the second, to Tim and Azmat's surprise. Ethel walks in – she wants some service. She orders a salad, and tells Ben that Milly won't be working at the café tonight – she has a dilemma to sort out. In the dorm room, Milly is talking to Tabby. She wishes she was back at Cackle's, and looks out of the window wistfully, when she sees a familiar figure on her broomstick riding over Cambridge. She rushes down into the Quad to welcome her.
Enid Nightshade lands in the Quad, to a welcome from Tim and Azmat. She tells them that she wants to see Milly. One of Beetle's many alarms goes off, alerting her to the fact that there is an unidentified visitor to the college. Milly runs down to the Quad and leads Enid off to her dormitory. Beetle arrives, just seconds too late to catch them. Milly asks Enid how her school is going. She says she's having a fantastic time, which is why she hasn't answered any of Milly's letters. She also says she's not doing much work, just partying all the time! They walk in on Cas doing some magic practise in their rooms – they've got an exam the next day. Enid announces that she'll sleep on the sofa. Ethel arrives and at first doesn't recognise Enid, and is displeased to see her there. Cas isn't happy either – it's exam time. Milly says she'll take the blame if the Beetle finds out. Enid drags Milly outside for some fun.
In Misery's Tim and Azmat are doing some magic tricks. They make a glass bottle disappear, but they're cheating as they're using real magic! Enid and Milly walk into Misery's, Tim and Azmat run over to say hi. Milly wants to go back to the college, but Enid wants to stay out. But when she starts to flirt with Ben, that is the last straw, and she drags her back to the college. Beetle nearly catches them as they sneak back in, but they get to the dormitory in time. Enid accuses Milly of having changed and becoming boring, but Milly says that she knows that Enid isn't just there to see her. Enid admits that her college isn't great at all, she's been unhappy there, and she just had to escape. She apologises for not telling her earlier. Cas and Ethel walk in – they have been woken up by Enid and Milly. Cas issues an ultimatum – if Milly values her friendship, Enid will only stay one night.
Next morning, Tim and Azmat are impressing Enid with some magic tricks. They are planning a stage act at Misery's! Enid says that she'll still be here tonight; she doesn't plan on leaving soon. Cas tells Milly not to let Enid start making herself at home, she has to go. Milly has had a note from Jenny Wendle that she didn't see – they changed her exam time, and she has missed most of it! Milly rushes to the lecture theatre, she is just in time. Thunderblast lets her take the exam.
The Beetle catches up with Milly after her exam and tackles her about the unknown guest. Milly denies all knowledge of it. At Misery's, Tim and Azmat are practicing their magic tricks in front of Enid, and Tim accidentally makes his arm disappear! Milly appears and tells Enid that they need to talk. She asks her to leave, because she's causing too many problems. Enid tells her that she can't leave, because she has nowhere to go. What she didn't tell her before, was that she was expelled from Primrose Hill for doing no work. She has to go home.
Ethel decides that enough is enough and goes to tell Beetle about Enid's visit. Milly tries to help Enid, but to no avail. Enid asks her to come away with her; she says that Milly doesn't belong at Weirdsister. The Beetle catches them and tells Milly that she has a choice to make – leave with Enid and follow a childish fantasy of travelling the world, or grow up and continue with their education. Milly knows that she has to stay at the college, but Enid feels betrayed, and goes to get her bag.
Cas and Milly are stood by the Wheel. Milly has passed her examination, and she now has to give her gift to the Wheel. She places Tabby on the Wheel, but Thunderblast tells her that she doesn't have to give up Tabby after all. Enid enters. She is offering up their old friendship to the Wheel. Enid explains that they will still be friends, but in a new way, what they had will be a nice memory. Milly runs over to give her a hug, and Enid steps onto the Wheel, to go home to her parents.
- Mildred: I will do anything. I will talk to your parents. I'll come home with you and see them if you like. But you can't stay at Weirdsister. You've seen the kind of college it is.
Enid: Come with me, then. Get out of here. Mildred: What, for good? Enid: Be honest with yourself. You don't really like it at Weirdsister. And you're more stuffled here than you were at school. Mildred: That's not true. Enid: Isn't it? Do you really want to stay at a place that's going take Tabby away from you? Mildred, you don't belong here. Anymore than I did at Primrose Hill. Mildred: No. Speak for yourself. Enid: It's not too late. I've left and so can you. We can go together. Now, today. Before you lose Tabby. We can explore the world together. Be real friends again. Wouldn't that be a lot of fun? (the Beetle walks up) Beetle: That's a very nice speech. Mildred: Beetle. Beetle: Just immature and romantic. Am I right in thinking you're Miss Enid Nightshade? Enid: Yes. Beetle: I know all about you. Well, Miss Hubble, from what I just heard, it seems you have a stark choice. Follow your young chum here on a desperate adventure to hang on to a doomed childhood, or face reality and continue with your education here. If you opt for the former, you can go and pack your bags immediately. If the latter, I suggest you persuade Miss Nightshade to leave forthwith. 
- Enid: I can't.
Mildred: Can't? Enid: I can't leave. I've nowhere to go. Mildred: Primrose Hill. I know you don't like it, but... Enid: No, Millie. It's more, much more than that. It's true, what I told you last night. What I didn't say...is they've kicked me out. 
- Mildred: (to Tabby) You know, sometimes I just wish we were back at Cackle's.