Letters to Mark is a documentary record centered on the writings of Mark Williamson, a man who claimed he had been subjected to a lifelong system of mind control and ritual abuse since childhood. Originally assembled in 2016 from a report sent to The New Yorker, this book preserves Williamson's unpublished manuscript, website materials, and email correspondence, while documenting the broader world of testimony and research surrounding trauma-based programming. This Critical Edition adds newly recovered archival material, a fourth chapter from Williamson's unfinished book, an investigative conversation using AI, and the transcript of Dr. D. Corydon Hammond's watershed lecture, in which a respected clinician trained in hypnosis reported encountering the same highly specific patterns across unrelated Multiple Personality Disorder patients, suggesting an organized system operating at scale.