Unaware of Shadow Weaver tracking her with the Shadow spy, Adora stresses out. Glimmer takes her to the hidden kingdom of Mystacor guarded by her overbearingly welcoming aunt, Castaspella, to try to help console her. Whenever Adora tries to relax at her friends' request, she insists that she can't because she believes that Shadow Weaver is in the kingdom, which everyone tells her is impossible. As a ceremony to renew Mystacor's barrier draws near, Shadow Weaver enacts a plan by using a Shadow spy to disrupt the ritual while isolating Adora for capture.
While Castaspella was showing Adora around Mystacor, one of the things she revealed was the past about Light Spinner, who is now Shadow Weaver. This makes Adora even more nervous. When Adora goes into the luminarium, she sees a shadow spy with voices of Catra and Hordak in menacing tones, and panics, accidentally destroying a thousand years' worth of sacred lunar crystal writings, nearly destroying the lenses that protect Mystacor. This makes Castaspella furious at Adora, and she goes into her room, where a shadow spy fake Glimmer brings her even more negativity.
The shadow spy tracks Adora into Mystacor and stalks here there. Adora tries to relax and get to know Castaspella and her kingdom, but Shadow Weaver uses the shadow spy to attack Bow, Glimmer, Castaspella and other sorcerers during the restorative ritual. The shadow spy had created an illusion taking the form of Glimmer and Bow that told Adora to leave Mystacor, which she started to do before hearing the commotion in the lunarium. Adora finds the shadow spy trying to interrupt the ritual, but She-Ra transforms the Sword of Protection into a shield and uses it to redirect the eclipse energy; recharging the magical enchantments that protect the kingdom.
- The history between Castaspella and Shadow Weaver was part of their backstory in the original She-Ra: Princess of Power series. However, the name "Light Spinner" was only used in the UK Masters of the Universe and Princess of Power comic magazines. The Masters of the Universe classic line, which began in 2008, elaborated on Shadow Weaver's origin by by revealing her true name to be Beatrix, with Light Spinner being a pseudonym she used while studying under Norwyn with Castaspella.
- The Sword of Protection transforms for the first time in this episode.
- The waves on the beaches of Mystacor are multi-colored clouds.
|She-Ra and the Princesses of Power's episodes|
|Season One||The Sword: Part 1 • The Sword: Part 2 • Razz • Flowers for She-Ra • The Sea Gate • System Failure • In the Shadows of Mystacor • Princess Prom • No Princess Left Behind • The Beacon • Promise • Light Hope • The Battle of Bright Moon|
|Season Two||The Frozen Forest • Ties That Bind • Signals • Roll With It • White Out • Light Spinner • Reunion|
|Season Three||The Price of Power • Huntara • Once Upon a Time in the Waste • Moment of Truth • Remember • The Portal|
|Season Four||The Coronation • The Valley of the Lost • Flutterina • Pulse • Protocol • Princess Scorpia • Mer-Mysteries • Boys' Night Out • Hero • Fractures • Beast Island • Destiny Part 1 • Destiny Part 2|
|Season Five||Horde Prime • Launch • Corridors • Stranded • Save the Cat • Taking Control • Perils of Peekablue • Shot in the Dark • An Ill Wind • Return to the Fright Zone • Failsafe • Heart Part 1 • Heart Part 2|