Thomas McGregor and Bea are now married and live in harmony with the mischievous Peter Rabbit and his animal friends. While Bea's book about Peter and his cohort has become a success, Peter struggles with his reputation as a naughty rabbit. Feeling misunderstood and seeking to escape his notoriety, Peter ventures beyond the garden. Once beyond the fence, he encounters a world where his mischief is appreciated, meeting an old friend of his father's who encourages Peter's rambunctious side.

As Peter finds himself embracing the thrill of the unknown, his family ventures out to find him. The McGregors, along with Peter's animal friends, face a challenging adventure as they encounter a variety of obstacles while trying to bring Peter home. They must navigate new environments and confront those who don't have their best interests at heart. Through their journey, they discover the importance of family and understanding one's identity beyond public perception.