A twinge of sadness, a rush of love, a knot of loss, a whiff of regret. Memories have the power to move us, often when we least expect it, a sign of the complex neural process that continues in the background of our everyday lives. A process that shapes us: filtering the world around us, informing our behaviour and feeding our imagination. How do our brains store – and then conjure up – past experiences. As a practising psychiatrist, Veronica O’Keane has spent many years observing what happens when this process is disrupted by mental illness and the experiences of her patients have provided startling insights into how memory determines how we function in the world. Drawing on these poignant cases and much more, from literature and fairy tales, she uses the latest neuroscientific research to illuminate the role of psychiatry today and the extraordinary puzzle that is our human brain.