In "Despicable Me 3," former supervillain Gru and his wife Lucy face a new challenge when they encounter Balthazar Bratt, a former child star turned villain. Bratt seeks to take over the world using his obsession with the 1980s, and Gru must stop him while also dealing with his own identity crisis. Meanwhile, Gru discovers he has a twin brother named Drew, who is eager to join him in villainy. Together, they navigate their differences and work to thwart Bratt's plans, all while Minions provide comic relief throughout the adventure.