After an introduction from the Diamonds ("The Tale of Steven"), Steven Universe, now 16 years old, greets the citizens of the Gem
Empire. The Diamonds want him to stay to fulfill his mother Pink Diamond's role as a leader alongside them ("Let Us Adore You"), but Steven refuses. Back on Earth, the Crystal Gems celebrate their newfound peace ("Happily Ever After"). Almost immediately, a giant drill lands on the hillside, and Spinel, a deranged and cartoonish Gem, appears, announcing her intent to kill Steven and the rest of the Earth ("Other Friends"). Using a scythe-like weapon, she "poofs" Pearl, Garnet, and Amethyst back into their gem forms. Her attacks also weaken Steven's Gem powers, though his body is unharmed. Steven eventually manages to poof Spinel with the scythe. Steven calls his father, Greg, for help. The Gems regenerate their bodies (including Ruby and Sapphire separately), but their memories have been erased; Pearl assumes that she is Greg's servant ("system/BOOT.pearl_final(3).Info"). With her memories gone, Spinel is a goofy and happy-go-lucky Gem whose function is to entertain her companion. Steven seeks advice from Peridot, Lapis Lazuli, and Bismuth, and they try to raise Steven's spirits ("Who We Are"). Bismuth recognizes Spinel's weapon as a "Rejuvenator", a device used to reset the minds of rebellious Gems back to their default state. Spinel compares the situation to a puzzle, suggesting that they find the Gems' "missing pieces" to restore their memories, inspiring Steven to try to reenact Ruby and Sapphire's first fusion. Spinel's antics cause scaffolding to collapse, almost crushing Ruby. When Sapphire pushes her to safety, they fuse into Garnet ("Isn't It Love?"), but she still has no memory of her life. After Steven recovers Amethyst's memory by reenacting experiences the two had together ("No Matter What"), Peridot discovers that Spinel's drill is injecting a toxic chemical that will kill all life on Earth. In a moment of panic, Steven attempts to remove the injector, but his weakened efforts only serve to accelerate the process. Realizing that Pearl is the only one who knows who Spinel is, the group takes her to a "Sadie Killer and the Suspects" concert, hoping their music will bring back her memories of rebellion ("Disobedient"), but Pearl insists that as long as Greg exists, she will obey him. Steven uses what little energy he has left to fuse with Greg ("Independent Together"), which enables Pearl to recover her memory. Overcome with sadness, Spinel flees; Pearl tells Steven that Spinel was once Pink Diamond's playmate. Steven follows Spinel to a desolate garden in space, where she recovers her memory and reveals her backstory: when Pink Diamond began the Gem colonization of Earth and did not want Spinel to join her, she tricked Spinel into "playing a game", in which Spinel was to stand frozen in the garden. Spinel was left alone there for 6,000 years before learning that Pink Diamond no longer exists ("Drift Away"). Steven tells her that Pink was wrong to treat her that way, and she needs to find someone else who will treat her better ("Found"). Back in Beach City, Spinel turns off the injector, but when Steven begins shifting his attention back to everyone else, she accuses Steven of using her, suggesting he'll abandon her or wipe her memory again. Spinel, now seething with rage, turns the injector back on and attacks Steven. As he tries to explain the truth to her, Garnet recovers her memory ("True Kinda Love"). Steven sends the others to rescue the humans of Beach City while he confronts Spinel. Steven finally realizes why his Gem powers have not yet returned: his desire for an unchanging "happily ever after" has left him resistant to the notion of growth and change, which he needs to re-experience. Embracing this fact, he regains his powers and battles Spinel, trying to convince her that she too can change ("Change"). Their fight destroys the injector, and Spinel relents after realizing how much she hates what she has become. The Diamonds suddenly arrive, intending to live on Earth with Steven. He introduces Spinel to them, and they take an immediate liking to her because of her goofy personality and how she reminds them of Pink Diamond ("Let Us Adore You (Reprise)"). The Diamonds accept her in place of Steven, and she happily goes with them, now with a family who will love her. Steven and his friends gather to rebuild Beach City, and he, Connie, Pearl, Garnet, Amethyst, and Greg perform a
Takarazuka-style "Finale". == Voice cast ==