Complex sentence: The book is a sequel to "The Tale of Peter Rabbit" (1902), and tells of Peter's return to Mr. McGregor'a garden with his cousin Benjamin to retrieve the clothes he lost there during his previous adventure.
Split into simpler sentences: The book is a sequel to "The Tale of Peter Rabbit" (1902). Peter returns to Mr. McGregor'a garden with his cousin Benjamin to retrieve the clothes he lost there during hia previous adventure.