The film opens with the wedding of Thomas (Domhnall Gleeson) and Bea (Rose Byrne), with all their friends, human and animal, in attendance. Peter Rabbit (James Corden) tells Benjamin Bunny (Colin Moody) that he is totally fine with Thomas marrying Bea, until the priest mentions Thomas becoming like a father to the animals. Peter appears to go berserk and attacks Thomas, leading the other animals to attack the humans until Peter makes Thomas float away on balloons. This is, of course, in Peter’s head, and he still accepts this new part of his life.

After their honeymoon, Thomas helps Bea as she works on her children’s storybooks based on Peter and his friends. Peter is a bit dismayed to know that the books have portrayed him as “naughty”. Outside, he talks to a mouse friend who talks about his life as a married mouse with kids, and Peter doesn’t want to think about Thomas and Bea starting their own family without him. Bea then gets a letter in the mail from a publisher who wants to distribute her books.Thomas and Bea take Peter, Benjamin, Flopsy (Margot Robbie), Mopsy (Elizabeth Debicki), and Cottontail (Aimee Horne) to meet the publisher, Nigel Basil-Jones (David Oyelowo). The other rabbits, barring a suspicious Cottontail, seem to like Nigel, until he presents his marketing plan toward the rabbits, which paints Peter as a troublemaker. They even see a billboard for a potential Peter Rabbit movie, which makes him look outright villainous. Flopsy and Mopsy, meanwhile, don’t like that people can’t seem to tell them apart or always associate one with the other.

A dismayed Peter walks away from the group and goes into town, where he meets an older rabbit named...