Marinette babysits Nino's younger brother Chris while he and Alya go to see a movie. When Chris finds a chest full of birthday gifts for Adrien, Marinette claims that she is secretly one of Santa Claus' helpers and that the chest contains Christmas gifts. Overwhelmed by the desire for Christmas to come early, Chris is akumatized into "Christmaster", a villain who controls an army of toys and seeks Santa Claus. Ladybug and Cat Noir are forced to team up with Santa in order to defeat him. Afterwards, Marinette admits that the chest contains gifts for a boy, much to Chris' disgust.