The major plot twist of the film is Adrien's decision to renounce his Miraculous. After a heated argument with Ladybug, who is furious that he left Paris unprotected, a guilt-ridden Cat Noir gives up being a hero and hands Plagg over to Ladybug. This leads to a powerful emotional climax where Marinette, also on the verge of giving up, realizes she cannot be Ladybug without him.
Another key revelation is that the magical charm that protects the Miraculous holders' identities is not infallible. The android hero, Uncanny Valley, is able to see through their disguises and identifies them as Marinette and Adrien. This adds a new layer of vulnerability for the heroes. The film's antagonist, Hawk Moth, succeeds in his secondary objective of acquiring the Eagle Miraculous, which he uses to turn the American heroes against each other. Although he is ultimately defeated, he escapes with the knowledge that other Miraculouses exist around the world, setting up future conflicts. The ending sees Jessica Keynes, formerly Sparrow, become the new wielder of the Eagle Miraculous, with the blessing of the native guardians of the American Miraculous box.