Peter Rabbit and Benjamin are all grown up now and Benjamin has married his cousin Flopsy (incest?) and produced a brood of Flopsy bunnies. The little bunnies fall asleep and are put in a sack by the evil McGregor! But don't worry--they get rescued in the end!
If you are already preparing your four-year-old for his SAT's, this story is great for the vocabulary section. I think "soporific" was used no less than three times, along with other difficult words.