After he is fired from the Anti-Villain League for failing to take down Balthazar Bratt (Trey Parker, “South Park,” Team America: World Police), the latest evil mastermind to threaten humanity, Gru finds himself in the midst of a major identity crisis. But when a mysterious stranger shows up to inform Gru that he has a long-lost twin brother — a brother who desperately wishes to follow in his twin’s despicable footsteps — the former super-villain rediscovers just how good it feels to be bad.