In these mathematical and logic puzzles, truth-telling knights battle lying knaves; a philosopher-logician named George falls in love with Oona, flighty bird-girl of the South Pacific; Inspector Craig and timid, conceited or modest reasoners match wits. Using such fictional enticements, the author of What Is the Name of This Book? and To Mock a Mockingbird steers us through the logical thickets of Kurt Godel's famous Incompleteness Theorem, which holds that mathematical systems can never prove their own consistency. Readers who make it halfway through this book will learn more symbolic logic than a college freshman stuffed with "new math." In the second half, the deeper waters of modal logic are navigated. This field, which dates back to Aristotle, impinges on current debates in computer science and artificial intelligence. Smullyan's gift is to make complex ideas both accessible and enjoyable to the persevering reader.