While everyone is celebrating Phobos's defeat, a kitchen worker named Trill gives the newly crowned Queen Elyon a jewel what belonged to her mother, Queen Weira. Caleb reveals to Cornelia his intentions to stay in Meridian and serve Elyon. Taranee starts thinking she will turn into an "invisible girl" again, and begins to act up at school. The Guardians are faced with an old enemy, Frost the Hunter, who followed them to Earth. Frost kidnaps Irma, Cornelia, and Hay Lin and threatens Taranee to bring Will to him without Heart of Kandrakar. In a subplot, a new foe called Nerissa appears. She frees Miranda, Gargoyle, the Tracker, Sandpit, and Raythor. Miranda betrays Phobos and does not free him. Nerissa and the others meet Frost. Now the enemies who Nerissa released are called Knights of Vengeance.

The Guardians are taken by surprise by their new powers: Will can bring electrical appliances to life, Irma now can use mind control, Taranee now can use telepathy, Cornelia now can use telekinesis, and Hay Lin can become invisible. The Knights devise a plan to blackmail the Guardians using Elyon's disappearance to make Earth authorities and their parents suspicious of their recent activities. After things are cleared up, Elyon decides to finish the rest school year, Caleb accompanying her. Meanwhile, Will is grounded because her poor grades and her mother sets her to transfer schools.