Born in 1945 in Wales, Marks is an academic prodigy who earns an Oxford scholarship. Introduced to cannabis by Ilze, he initially vows to quit harder drugs after a friend's overdose. After his associate Graham Plinson is arrested in Germany, Marks successfully smuggles hashish into London, sells it to Saleem Malik, and builds a massive cannabis trafficking empire. He later faces government agents, serves a US prison sentence starting in 1988, and eventually becomes a media personality.