John Gribbin is known for giving us simple explanations of big concepts in science. But faced with persistent enquiries from his grandchildren, Gribbin realised that simple questions, such as 'Why is the sky blue?', sometimes require big answers, understandable in straightforward language. In answering those simple questions, he discovered that he was telling the story of our place in the Universe, from the Big Bang to the evolutionary reasons why men are, on average, bigger than women. The questions may be obvious, but the answers are sometimes surprising and highlight one of the main joys of science - discovering the unexpected. Gribbin invites the reader to join him on this voyage of discovery, where you may think you already know the answers but should be prepared to be surprised - or at least, tantalised by the truth.