Happiness is one of life's greatest mysteries. But what even is happiness? Why does it mean so many different things to different people? And how can we actually be happier? Drawing on decades of experience in crime writing, self-help and intensely curious observation of other people, Sophie Hannah sets out to solve the mystery. She lines up her cast of suspects and expert witnesses from ancient philosophers to modern self-help gurus, scientists to ordinary people from all walks of life. Leaving no stone unturned, she scrutinises the clues, evidence, and even the red herrings that unexpectedly lead to happiness. And she uncovers answers - from the secrets of a fulfilling relationship to the joys of boredom, or of the bliss of a cancelled meeting. Weaving in much-loved poems and hilarious observations from Sophie's own life, this is the ultimate guide to happiness - and the clues that can lead us there.