Film pripoveduje življenjsko zgodbo angleškega preprodajalca mamil Howarda Marksa. Howard je pameten fant in dober učenec. V šestdesetih dobi štipendijo za Oxford, kjer se prvič sreča z marihuano in hašišem. Naposled postane preprodajalec, s preprodajo pa se ukvarja po celem svetu in to kar dvajset let. Vmes se poroči in si ustvari družino, a roka pravice mu je vse bolj za petami.
Mr Nice is the true life story of Howard Marks who was born into a coal mining family in South Wales in 1940's and then made it to Oxford University to study nuclear physics during the swinging sixties. With the help of fellow students, Marks built a worldwide marijuana smuggling network which became responsible for the majority of the drug smoked in the Western world during the 1970s and 1980s. Marks' adventures led him to have dealings with the CIA, PLO, IRA and the Mafia and he even became an MI6 agent himself for a period. Howard Marks is played by the brilliant Rhys Ivans, who won much acclaim for his portrayal of the folk hero.