While everyone is celebrating Phobos' defeat, a kitchen worker named Trill gives Queen Elyon a jewel what belonged to her mother, Queen Weira. Caleb reveals his intentions to stay in Meridian and serve Queen Elyon to Cornelia Hale.
As Taranee starts thinking she will turn into an "invisible girl" again, the Guardians are faced with an old enemy, Frost, the Hunter, who followed them to Earth. Frost kidnaps Irma, Cornelia and Hay Lin and gives Taranee a ransom: Take Will to the cave, but without the Heart of Kandrakar or she'll never see her friends.
After taking Will to the cave, Frost captures Will and Taranee and Taranee gives Will the Heart back. Then, as expected, the girls transform and free themselves. While on the battle, a portal suddenly appears and Frost escapes. Taranee admits all to her friends and Cornelia decides to be still The Guardians.
In the B-story, a new foe called Nerissa appears as she frees Miranda, Gargoyle, the Tracker, Sandpit and Raythor and meets Frost. Now the enemies who Nerissa released are called Knights of Vengeance.
- This episode marks the first official of an appearance of Nerissa.
- The power of Quintessence is introduced in this episode.
- Beginning with this episode, Will now says, "The Heart of Kandrakar".