Meanwhile, in Meridian, Caleb, the leader of the Rebellion against the evil Prince Phobos, is running for his life after a failed attempt at a storage raid.
Overcome with fear, Will does not close the portal until one of Phobos' servants, Lord Cedric, drags Caleb through.
Caleb discovers that fellow rebels have been turned into zombified Trance Marchers by the sound of a magical object called the Horn of Hypnos.
Only a specific melody can break the spell, but how long will Will, Irma, Taranee, Cornelia and Hay Lin be able to resist the entrancing sound of the Horn of Hypnos?
Meanwhile, as it is Halloween, the one night in the year when a Heart can be taken by force, the Guardians have to protect Napoleon, as he is Lilian's familiar.
Meanwhile, Irma is forced to take her brother Chris, Lilian, and Blunk trick-or-treating, only to discover that her crush Andrew Hornby likes to trick-or-treat too.
After Cedric swallowed Phobos, thus gaining the power of Nerissa's seal, he decides with Miranda to seek revenge on everybody.
With Cedric defeated, C.H.Y.K.N., Elyon and Yan Lin's Altermere escape, except Nerissa who becomes trapped in her own dream.