Will Vandom experiences a frighteningly realistic dream, and gets in trouble for sleeping in class. Her mother, thinking Heatherfield isn't working out for them, decides to transfer back to Fadden Hills. The other girls realize that they were having the same nightmares, and Will tells them about returning to Fadden Hills.
W.I.T.C.H. then decides to sabotage the transfer request, so they go Susan's building. After waiting for hours, all the girls had fallen asleep, with Taranee Cook falling asleep last. They all have nightmares, and barely wake up: Taranee learns that anything that happens in the dream happens to them in real life. She discovers that someone is invading there dreams, using their deepest fears to conjure up dream images of there imagination.
Taranee leaves to find a new way to combat the new threat while the rest of the girls take care of the transfer request. Taranee returns, and suggests lucid dreaming, making it possible to control their own dreams. They also sleep close to each other, allowing the psychic invasion to localize them all into the same dream.
In the dream, they discover that it was all Nerissa Crossnic's doing, and blast her with psychic feedback to end the nightmare. After W.I.T.C.H talks to Susan about her plans and asks her to give Heatherfield another chance, and she agrees.
- Nerissa's presence is revealed to the W.I.T.C.H. girls, but they are unaware of her name until K is for Knowledge.
- Nerissa's terrifying ability to manipulate a person's dream and turn it into a nightmare is shown in this episode. This ability is also in the comics.
- This episode marks the first time the Guardians are shown in their Zenith forms (the second time is in Z is for Zenith).
- Although Lord Cedric isn't a part of the Nerissa's Knights of Vengeance, he appears in Will's dream at the beginning of the episode.
- This episode shares similarities with issues #13, #14 and #19 of the comics. Susan Vandom's decision of leaving Heatherfield and moving back to Fadden Hills was revealed in #13 and the W.I.T.C.H. girls attempts at preventing this also occurred in the subsequent issue. Also, a similar battle between the W.I.T.C.H. girls and Nerissa occurred in issue #19, only instead of it being in their dreams, it took place in the Realm of Nightmares.