Ah, this book made me glad I was reading them all in order of publication. This is book 4, and for the first time, characters from a previous books turn up! We learn a bit more about Peter Rabbit's widowed mother, for instance - she makes a living selling, among other things, rabbit tobacco (known as lavender to us oblivious humans!). Benjamin Bunny is Peter Rabbit's cousin, and even more mischievous than him. Peter is still unwell (and without clothes - wearing a hankerchief to hide his nakedness!) from his escapades in Mr McGregor's garden. Benjamin Bunny gets straight to the point, and asks who's got his clothes. When Peter explains, Benjamin informs him that Mr McGregor is out for the day - very subtle way of suggesting they go retrieve the clothes! So off they go, despite the fact that poor Peter is poorly and now terrified of that garden!
And then of course they have adventures, despite Mr McGregor being out for the day! I won't give away any spoilers but will mention that, gosh, Benjamin Bunny's dad is quite a fierce character - nowhere near as lenient as Peter Rabbit's mother!