Please do not say that you are looking for a book called "Metamorphosis or something" and send me dashing happily off to Kafka and then to Ovid, full of delight that oh here is a request I don't even have to look up on the computer how lovely, only to have you say, sometime later, that it's actually a business book you're looking for.
The quickest way to find a book: ISBN number. Saying that you read about it in the NY Times a few months back, that it had the word "red" in the title, and that it may have had something to do with murder is not quick. It can be fun. It can be a treasure hunt. It may turn up all kinds of excellent books you and I would never have glanced at otherwise. But it's not quick. Just so you know.
Your children have good taste. I don't care whether they're clutching piles of Rainbow Fairies books or hanging onto D'Aulaires' Book of Greek Myths. They're reading, figuring things out, standing at the shallow edge of a crazy, wonderful ocean and deciding that they want to get wet. There are so many incredible books for kids and I would love to offer up my own favourites, but please, please don't say "no, you can't read this." It will only make them want to read it more anyway.