Cosmo's fagiggly gland, the fairy organ that controls shape-shifting, is on the fritz. Cosmo needs to get a donation from his closest biological known biological match or else he can't be a fairy godparent anymore, and the only other being with a fagiggly gland available is Anti-Cosmo. However Jorgen will not let Anti-Cosmo out, so Timmy and his godparents must now find a way to break Anti-Cosmo out so they can do the transplant.
Timmy is wondering if Vicky's Dad could move to New Zealand, making Vicky having to move to New Zealand as well. Cosmo thinks it is an excellent plan, but suddenly, Mr. Turner is coming into the kitchen where Timmy is. Wanda tells Cosmo to change into something new. He changes into cake, but Mr. Turner eats him. In Timmy's room, Timmy tells Cosmo that he needs to be more careful of what he changes into. He says he knows, and tries to kiss Wanda. When he does, he accidently shapshifts into a fork poking Wanda. Timmy thinks that something is wrong with Cosmo, and he says no. Then he turns into a chainsaw almost cutting Wanda, but only her crown is destroyed. Cosmo then turns into other dangerous things and apologizes to her. When he tries to kiss Wanda again, he turns into an electric eel.
Timmy wants to know why Cosmo is constantly changing into the wrong things. Wanda thinks that there is something wrong with Cosmo's fagiggly gland. He says it's fine. But when they go to Dr. Rip Studwell's office, he says that Cosmo's fagiggly gland is not alright. Timmy asks him what is a figiggly gland. Dr. Rip Studwell explains that it is an oragan in the fairy body that allows it to shapeshift. Wanda wants to know if Cosmo is sick. The Doctor says it in words that Cosmo could understand, by saying "yes" like a crazy person would. Cosmo thinks that since his fagiggly gland is out of control, he would have to quit being a fairy god parent and go to his old job. The doctor says that Cosmo has good news and bad news. The good news its the doctor is going to play golf at 2:30. The bad news is that there is only one way to stop Cosmo's fagiggly gland from going crazy. The way is to have a fagiggly gland transplant. Wanda says that Cosmo has no siblings, so they go to Fairy World Prison to see Anti-Cosmo. He knows Cosmo's fagiggly gland is going bad. Cosmo asks how he knows, and he tells him that he is smarter than Cosmo. Anti-Cosmo's is going good.
The only way to get out of prison is to tell Jorgen, who was there, that Cosmo needs to have a fagiggly gland transplant with Anti-Cosmo. Jorgen says no, and he kicks Timmy, Cosmo, and Wanda out. Timmy has a plan to bust Anti-Cosmo out of prison. He gets a large drill to dig into the ground and inside prison. He can't hear what any other person inside the drill were saying, which is dangerous because Wanda was trying to say that all of Fairy World is on clouds, and that you can't drill on them. Cosmo tries to kiss Wanda, but turns into a fork again, but this time couldn't hear Wanda screaming. When Timmy drills, they fall through a cloud and land safely on another cloud. Wanda suggests a much better plan. During the track meet inside prison, Cosmo turns into a fork but Wanda has a shield this time. The Anti-Fairies try to escape prison. Anti-Cosmo tries to fly out of prison, but instead lands on a wall.
Timmy tries putting Anti-Cosmo on a hot air balloon, but fails when Cosmo turns into heavy things. Jorgen kicks them out of prison again. Dr. Rip Studwell appears on Wanda's wand and says that there is good news and bad news. The bad news is that if they don't make the transplant soon, it will be too late. The good news is that the doctor is doing well in golf. Suddenly, a sheet with another plan to bust Anti-Cosmo out of prison flies through the air and Timmy grabs it. The plan is to put Anti-Cosmo in a wheel and disguise Timmy, Cosmo, and Wanda as laundry workers. Jorgen comes out and asks questions. He tries to put a pitch fork in the laundry to see Anti-Cosmo in pain, but instead finds out Anti-Cosmo is not in there. Anti-Wanda says that Anti-Cosmo is in the wheel, spoiling the secret. He gets mad at her. Jorgen tries to vaporize them and they try to look for a safe place. Cosmo suggest they go to the gate, but Jorgen has the key. Cosmo tries to shapeshift into a key, but instead turns into things that rhyme with key. When he finally turns into a key, they escape prison with Anti-Cosmo and go to the golf course where Dr. Rip Studwell is.
Jorgen's fagiggly gland is out of control, and he tries to find Anti-Jorgen. At the golf course, they say that Anti-Cosmo is here. He poofs them to the hospital and they get ready for the transplant. After the transplant, the doctor says that there is good news, bad news, worse news, and horrible news. The good news is that Cosmo and Anti-Cosmo are fine and back to normal. The bad news is their insurance isn't going to cover it. The worse news is Anti-Cosmo escaped. The horrible news is Anti-Cosmo is on the phone. Cosmo takes it and talks to Anti-Cosmo.
He says that they each share a lot in common and that they shouldn't do battle. Then he says to not look for him. Cosmo looks behind his back and sees Anti-Cosmo. Anti-Cosmo said that he said to not look for him. Then says bye to Timmy and Wanda in Cosmo's voice and is freaked out. Wanda thought it is weird. Then Cosmo says to Wanda where she is in Anti-Cosmo's voice.