This book presents a comprehensive history and analysis of Secret Cinema - the leading producer of large-scale immersive experiences in the UK. It examines how the company has evolved over twelve years from an experimental and artisanal organisation to a global leader in the field. The book focuses on the UK in late-2019, a point at which the immersive sector had grown significantly through its increasing contribution to GDP and its widespread recognition as a legitimate cultural offering. It captures an organisation and a sector transitioning from marginal and subcultural roots to a commodifiable and commercial form, now with recognisable professional roles and practices, which has contributed to the establishment of an immersive experience industry of national importance and global reach.