While Ben and family are visiting Salem, Massachusetts, Charmcaster attacks in an attempt to magically switch bodies with Ben to attain the great powers of the Omnitrix. However, Gwen interferes, causing Charmcaster to switch with her instead. Gwen is punched out by Charmcaster before she can explain anything, and is then arrested and sent to juvie, where she meets two delinquent girls named Pinky and Missy. Meanwhile, Charmcaster stays with the unaware Ben and Max and tries to cook up another body-transference spell. Gwen stops Pinky and Missy from escaping using two clay animals as she escapes from juvie and returns, convincing Ben of the truth before Charmcaster tries again. However, Charmcaster manages to swap their bodies once more, ending with Charmcaster in her true body while Gwen and Ben have switched. The two swap back as a result of Charmcaster’s third body-swap spell and Cannonbolt defeats Charmcaster. Ben as Cannonbolt ties up Charmcaster. Gwen punches Charmcaster out as revenge for having punched her out earlier. Gwen ends up taking Charmcaster’s spellbook for her own use in hopes of further developing her own inherent magical abilities to help in fighting crime. Elsewhere, Charmcaster is back in jail where Pinky and Missy come in and prepare to give her a beating.
Note: As her alternate future self (adult Gwendolyn from Ben 10,000) had told her about being quite a natural at magic, Gwen proves this by taking Charmcaster’s miniature spellbook for her own use.