While the girls practice for an upcoming talent show, Onyx suddenly notices her gem's glow is fading and runs home to see if she can fix it. Amethyst and Topaz go to her house and confess that their gems have also been fading. While they wonder what to do, a TV broadcast shows Miss Tourmaline, who notes their problem and promises a quick fix. Onyx, Topaz, and Amethyst head to the shop, while Ruby and Sapphire catch up later—but it turns out to be a trap! Snarf disguised himself and projected the broadcast in an attempt to grab their gems. The girls escape him by running through the only door that isn't magically locked—but that's also a trap.
The Trollz find themselves in the mysterious Shadow World, lamenting that if they'd just talked to each other about the problem they could've gone to Obsidian instead of falling into a trap. Just being there drains their magic even further, but before they can think of a way out they hear a call for help. A young troll boy named Simon was also trapped here—so long ago he can't remember when. He wants to escape with the Trollz, and together they find a portal near a stone altar. It drops them out at the mall, which is now closed. Suddenly, Snarf runs up... and asks Simon if he did well. Simon isn't a troll at all—he's a power-hungry gremlin who was imprisoned in the Shadow World for 3,000 years, and the only way he could escape was for someone pure of heart to help him of their own free will.
Simon reveals that he was the one draining the girls' gems to take their magic, and he and Snarf move to finish the job. Luckily, Simon has no knowledge of or aptitude for modern technology like escalators or Skoots, which helps the girls elude him while they work on a plan. Amethyst casting a spell alone isn't enough to stop him, but Ruby reminds them of the Magic of the Five—and by working together, Amethyst, Ruby, Topaz, Sapphire, and Onyx send Simon and Snarf back to the Shadow World. Their gems are back to normal, and with the Skoots still near the mall, the BFFL head home safely.
This episode contains examples of:
- Animate Inanimate Object: Simon uses a spell to make mannequins come to life and stop the girls.
- Batman Gambit: Snarf sets up a fake store to lure the girls to him in disguise as Miss Tourmaline, claiming he can fix their gem glow when he planned to steal them. When the girls escape, they enter a portal through the only open door to the Shadow World, where they meet Simon who wants to escape along with them. Turns out, Simon knew they would be led into his trap to lure them to him so he can use their pure hearts to escape his 3,000-year imprisonment.
- Big "NO!": By Onyx when she comes home and realizes her gem’s glow is low.
- "Could Have Avoided This!" Plot: Amethyst says that if they had just talked to each other about their gems fading, they could've gone to Obsidian instead of falling into a trap.
- Debut Queue: First physical appearance of the Big Bad Simon, after only being vaguely mentioned in the past arc.
- Disguised in Drag: Miss Tourmaline is really a disguise of Snarf to trick the BFFL into giving their gems to him.
- Double-Meaning Title: The episode title refers to Onyx's gem losing its power along with the others, as well as "gem" referring to a helpful individual, referring to the BFFL.
- Foreshadowing: Miss Tourmaline’s name doesn’t fit the Fantastic Naming Convention where everyone has the word “Troll” as part of their last name, which hints she’s really Snarf in disguise.
- Wham Line: The Trollz think Simon's a nice little boy and help free him from the Shadow World. Then Snarf catches up to them and approaches Simon.Snarf, to Simon: Did Snarf do good, Master?
Simon: Better than good. Tonight, you get an extra goodie! - The Wrong Way on the Escalator: When chasing after the BFFL, Simon tries running up a down escalator and struggles.Simon: Why is this staircase working against me?!
