In the summer of 1965 the informal parties that Ken Kesey was holding at his house in Palo Alto California were about to evolve into what became known as the Acid Tests. These spontaneous anarchic gatherings spread their tentacles far and wide until an entire generation seemed to be under their spell. Fifty years on from the Merry Pranksters multimedia mayhem, acclaimed author Rob Chapman explores in crystalline detail the history, precedents and cultural impact of LSD, from the earliest experiments in painting with light and immersive environments to the thriving avant-garde scene that existed in San Francisco long before the Grateful Dead and the Fillmore Auditorium. In the UK, he documents an entirely different history, and one that has never been told before. It has its roots in fairy tales and fairgrounds, the music hall and the dead of Flanders fields, in the Festival of Britain and that peculiarly British strand of surrealism that culminated in the Magical Mystery Tour.

Sitars and Sergeant Pepper, surfadelica and the Soft Machine, light shows and love-ins - the mind-expanding effects of acid were to redefine popular culture as we know it. It's a story that you think you know, but no one has laid out the narrative quite like this before. Chapman documents psychedelia's utopian reverberations - and the dark side of its moon - in a shimmering day-glo portrait where the sublime, the sinister and the just plain silly co-exist in imperfect harmony.