Back in the sixties, LSD was all the rage — not just in the counterculture but also in psychiatric clinics. Then psychedelics were outlawed and decades of research vanished. Now, psychedelic science is back — and the early results are extraordinary. A single dose of psilocybin can help people with addictions, PTSD and end-of-life anxiety. We’ll examine this revolution in medicine, and explore the connections between psychedelics and mystical experience.