In the alternate reality, "The Supreme" rules supreme and possesses all jewels, handing the Ladybug and Cat Miraculouses to Marinette and Adrien under strict conditions of servitude. Gabriel Agreste stole the Butterfly Miraculous to launch a resistance movement alongside Nino and Alya.
When Shadybug obtains the earrings and ring, she attempts to invoke the ultimate wish to fix her fractured life; however, the spell fails because The Supreme placed an absolute limitation on the jewels to prevent anyone from overthrowing him.
Seeking refuge in Marinette's bedroom, Shadybug reads her diary and realizes that Marinette's strength comes from love, friendship, and family support—things Shadybug was denied. When Sabine speaks tenderly through the locked door, Shadybug weeps, realizing she is worthy of love and shedding her villainous persona. Concurrently, Cat Noir confronts Claw Noir, sharing his own secret feelings of loneliness and pressure under his father's expectations, validating Claw Noir's grief and transforming his rage into trust.
Reborn as true heroes with revamped bright suits, Shadybug and Claw Noir join Ladybug, Cat Noir, and Betterfly to overpower Monarch. They return to their own universe empowered with hope to dismantle The Supreme's tyrannical empire.