Reason for Reading: next (and, I'm guessing, last) in the series. Simple enough plot: Lisa and Nilly figure out that most of Norway has been hypnotized by space aliens whose ultimate goal is to take over the world so they can use humans as food. They alert Dr. Proctor and the three of them, with the aid of several others who have not been hypnotized set out to stop the dastardly aliens before they can invade Denmark and set their world domination plan into action. Hilarious! I read this book in two sittings and enjoyed it probably the most of all three books. There are no references to book 2 at all except for mention of Dr. P's lady friend who is still in France and not a character in this book, so there is no need to have read the books in order. I do recommend at least having read book 1 though as it explains the whole Fart Powder background, while this book just assumes you know the power of the invention. Also, the American publishers make a big deal of the "fart" allusions in the title of these books , but except for book 1 there is very little toilet humour within the books at all once you get past the idea of "fart powder". The name of this book in Norwegian is "Doctor Proctor and Armageddon. Maybe." which is an appropriate title while "Who Cut the Cheese?" is simply a marketing gimmick. However ... The story is deliciously funny. Nilly and Lisa are fantastic kid characters, with strange families and even stranger classmates and teachers. We have a few new characters along for the ride this time who add a new dimension to the team but as usual, Nilly and Lisa are the only main kid characters. The plot is way-out there silly and Doctor Proctor as usual has a few fun inventions to help them out. If you've enjoyed the other books in this series, you'll love this one! To me, there is a finality to the book which makes me think this may be the last book in the series. If so, I'm happy to leave the characters here and have enjoyed my time with them. For younger children, I suggest you just read books 1 & 3 and leave book 2 for older children who have some historical knowledge/interest in France.