I've always loved this book, ever since I read it in fourth grade; the thought of little people always appealed to me. The style the book is written in is sort of old-fashioned for today's readers, but if a person can read it, then I definitely recommend it.
It's about a type of people, Borrowers, that are very tiny. They live in houses and 'borrow' things, like food, paper, and basically anything that they can get their hands on. They picture people as giants that are put on this earth to make things for them to 'borrow'... They live under floor-boards, behind pictures, over mantles; basically anywhere. That's how Arrietty's mother and father tell it.
But, in all reality, there is only herself, her mother, and her father left in that one particular house. Every other Borrower family had emigrated to somewhere else... and Arrietty accepts that until one day she is seen by a boy that puts the thought into her head that maybe her family is the last of the Borrowers.
And that's really how it all starts. Arrietty and the Boy form a sort of friendship, where the boy takes a letter to the place where Arrietty's Uncle is supposed to live, and Arrietty reads to him. (The Boy says that he's bilingual, and that's the reason that he can't read well.) And taking the mail isn't the only thing that the Boy does- he also brings the Clocks furniture, food, and other things.
Things which are discovered missing later.
And that brings in the cat and the rat-catchers...
One of my favorite childrens' books; I think the reason I like it so much is that it doesn't take for granted that kids wouldn't be able to understand a longer book... I think that's also what I love about the Harry Potter books, as well.
Anyway, read this. Very sweet, very family friendly. Altogether enjoyable.