Marinette helps Alya babysit the latter's twin sisters, Ella and Etta. When they keep staying up and refuse to go to bed, Alya forbids them from going to the amusement park the next day and confiscates one of their hats. The twins, sad over the fact they now can't go the amusement park and have to listen to their older sister's orders, are fighting over the other hat, then Hawk Moth akumatizes them into Sapotis, a pair of small but totally unpredictable monsters that multiply and cause havoc. When Ladybug and Cat Noir are overwhelmed by the creatures, Ladybug is prompted by her Lucky Charm to visit Master Fu, who loans her the Fox Miraculous. Ladybug gives the Miraculous to Alya, who, with the command of Trixx the kwami, transforms into the fox-themed superheroine, Rena Rouge. After the three heroes overcome the Sapotis menace, Alya reluctantly returns the Fox Miraculous to Ladybug and keeps the details of her adventure a secret.