What happens when a new drug hits the UK’s streets? And how are illicit drugs here changing – and why? James follows the trail of the first case of “zombie drug” xylazine in the UK and hears some powerful personal stories along the way. The story begins in Solihull, in the West Midlands, where 43-year-old Karl Warburton was found dead in May 2022. He had a mix of xylazine, heroin, fentanyl and cocaine in his body. James visits a local addiction clinic where Mark describes the fear and compulsion many addicts face. He tells James about his journey to recovery and we meet Simon who’s on a mission to help people like Mark into a new life. Next, James meets toxicologists at a busy hospital lab in Birmingham where he finds out how xylazine was first detected. Then he travels to London to meet a university academic who first raised the alarm about the drug, and visits a cramped room containing the paper records she keeps detailing every drug death in Britain from the past 25 years. James goes on a surprising and, at times, emotional journey as he gets a rare insight into the world of illegal drugs and the parts of the NHS that treat addiction. Presenter: James Gallagher Producer: Gerry Holt Editor: Erika Wright Production Co-ordinator: Jonathan Harris Technical producer: Andrew Garratt Locations: Solihull Integrated Addiction Services, Birmingham and Solihull Mental Health NHS Foundation Trust Department of Toxicology, Birmingham Heartlands Hospital The National Programme on Substance Abuse Deaths (NPSAD), King’s College London