The movie is a sequel to Minions (2015), and spin off/prequel to the main Despicable Me movie series.
A continuation of the film of 2015, this time in the heart of the 1970s, a twelve year old Felonius Gru is growing up in the suburbs. A fanboy of a supervillain group known as the Vicious 6, Gru hatches a plan to become evil enough to join them. When the Vicious 6 fire their leader, legendary fighter Wild Knuckles, Gru interviews to become their newest member.
It does not go well, and things only get worse after Gru steals from them with the help of Kevin, Stuart, Bob, Otto, and the other Minions and suddenly finds himself the mortal enemy of the apex of evil. On the run, Gru and the Minions will turn to an unlikely source for guidance, Wild Knuckles himself, and discover that even bad guys need a little help from their friends.