Are you still the person who lived fifteen, ten or five years ago? Fifteen, ten or five minutes ago? Can you plan for your retirement if the you of thirty years hence is in some sense a different person? What and who is the real you? Does it remain constant over time and place, or is it something much more fragmented and fluid? With his infectious curiosity and bracing scepticism, Julian Baggini sets out to answer these fundamental and unsettling questions in a fascinating quest.