The Reader in European Pre-History at the University of Oxford, Dr Andrew Sherratt, was the series host. Prior to his resignation from the University of Oxford, Sherratt was appointed Professor of Archaeology. Each episode began and ended with Sherratt inscribing his diary with his reflections on the series' scientific and cultural investigations. In each episode the series investigated one psychoactive plant and its cultural significance. Three specialists of various scientific disciplines were invited to monitor two volunteers who had taken each plant. After the four episodes, Sherratt assigned considerably more significance to the psychoactive properties of plants in ancient civilization and the prehistoric period than expert knowledge hitherto.