Gru, Lucy, Margo, Edith, and Agnes welcome a new member to the family, Gru Jr., who is intent on tormenting his dad. Gru faces a new nemesis in Maxime Le Mal and his girlfriend Valentina, and the family is forced to go on the run.
Gru and Lucy are overjoyed as they welcome their newest family member, Gru Jr. However, their happiness is short-lived when a new villain, the cunning Maxime Le Mal, emerges. With their family in danger, Gru and his team must utilize their wit and skills to outsmart the villain and protect their loved ones.—Oscar Serpa
The movie begins with Gru attending a reunion at his old school, Lychee Pas Bon. Whilst there, he reconciles with his old foe Maxime Le Mal, who had his act stolen by Gru as a child and has plotted revenge ever since. Maxime says that he has used cockroach parts to make him more powerful, in a bid to conquer the entire world, but Gru along with the rest of the AVL, arrests him. Unfortunately, with the help of his girlfriend Valentina, Maxime escapes from prison and shows his intention of turning the human race into human-cockroach hybrids. Maxime plans to try it out on Grus biological son, Gru Jr.
The ex leader of the AVL, Silas Ramsbottom comes to have a word with Gru and his family. Silas tells them of Maximes escape and the fact that they will have to relocate Gru and the family to a house in a different town named Mayflower under a new identity. The majority of the minions are taken in by the AVL, whilst Dave, Mel, Gus, Tim and Jerry are the chosen five to be part of the Megaminions, which get special powers. Unfortunately, the plan is quickly called off after they cause damage to the city.
In the new town, Gru and the family meet their new neighbors, the Prescotts who have a teenage daughter named Poppy who aspires to be a villainess. Poppy recognizes Gru and his work as a former villain and she threatens to blow Grus cover unless he helps her steal Lychee Pas Mals honey badger mascot, called Lenny, so she can be enrolled. Gru agrees and the duo, alongside two minions and Gru Jr successfully take Lenny. Unfortunately, the schools elderly principal Ubelschlecht uses the security cameras to identify Gru and ultimately tell Maxime of Grus whereabouts.
The following day, Gru and Lucy go out to practice Tennis with the Prescotts. While they are out, Ubelschlecht pays a visit to the house interrogate the girls about where Gru is located. Margo calls Gru and Lucy and they rush back home to fight Ubelschlecht. Lucy contacts the AVL, who get the Megaminions to help stop Maxime. Whilst no one is looking, Gru Jr sneaks out of the house and gets kidnapped by Maxime and Valentina.
Poppy helps Gru meet with Maxime, where he reveals that he has transformed Gru Jr into a roach hybrid. Maxime uses Gru Jr to fight off Gru, however Gru manages to convince Gru Jr to break out of his trance and turns on Maxime and attacks him instead. Maxime collapses to the ground, who then gets squashed by the Megaminions and the aid of a majority of animals and insects, who ultimately arrest him.
Now all safe, Gru and the family arrive back home and Dr Nefario helps turn Gru Jr back to normal. Gru then goes to visit Maxime in prison and the duo settle their differences. Gru and Maxime go on to perform "Everybody Wants to Rule the World" at a prison for all of the criminals there, including Grus former adversaries. Poppy is revealed to have been successfully enrolled at Lychee Pas Bon.
