The film centers around a theft—the world's largest diamond disappears despite top-notch security measures, leading to “Gru” and “Lucy’s” dismissal from the anti-villain organization. Undeterred, they resolve to retrieve it from “Balthazar Bratt.” Their daughter, “Agnes,” attempts to assist by selling her toys, but fortunately, before things escalate further, “Gru” learns he has a previously unknown twin brother named “Dru”. It becomes apparent that "Dru" is even more villainous than "Balthazar," and intends to involve his brother in profitable criminal activities—including stealing the diamond from whoever currently holds it. The narrative feels somewhat thin; at times, it's hard to follow and the minions have a limited role, making the story feel like a promotional effort rather than a proper continuation of the original film, which was released nearly seven years ago and possessed a distinct charm. A vibrant 1980s soundtrack helps maintain the pace, and younger viewers will likely enjoy the physical comedy—particularly in the final act—but adults may find less to appreciate, suggesting that this series might be nearing its end.

Source on TMDB