The Four Colour Problem was one of the most famous problems of mathematics of the 20th century. The problem even attracted the attention of the general public. Even the solution of the problem was accompanied by doubts, and it was the starting point for a discussion about the nature of mathematical proofs. The present book accurately describes the origin and the colourful history of the problem and various proof attempts. The book is written for a general public; the recent development (such as work of Robertson, Seymour and Thomas) is only briefly mentioned. It is a very good popular book. Its lively and accessible form will pave the way also to non-experts and to a non-mathematical audience.