The film features an ensemble cast starring Rhys Ifans as Howard Marks, along with David Thewlis, Omid Djalili, Jack Huston, Crispin Glover and Chloë Sevigny.

After serving time in Terre Haute, one of the "toughest" prisons in the United States, Marks stopped smuggling and dealing in cannabis (although he still openly used the drug himself) and gained wider fame as a pro-cannabis campaigner, stand-up comedian, actor (at least in cameos), lads' mag columnist, television show panelist, music producer, motivational speaker, and even prospective Member of Parliament.

Born in the Welsh valleys in 1945, young Howard Marks (Rhys Ifans), later nicknamed Mr Nice, excels academically beyond the national standard of the United Kingdom.

A beautiful, rebellious and hedonistic foreign exchange student from Latvia, Ilze Kadegis (Elsa Pataky), breaks into Marks's room, looking for a secret passageway within.

After Marks sells the hashish back in London to an Arab oil sheik named Saleem Malik (Omid Djalili), he makes a fortune and swiftly becomes addicted to this new but dangerous lifestyle as a big league marijuana trafficker, eventually running a large percentage of the world's cannabis trade.

It is a path that will lead Marks face-to-face with terrorists, government agents, and lose him his freedom to one of the toughest prisons in the United States in 1988, through to the present day as a media personality and cult hero.

[citation needed] The film features a 1960s pop-inspired soundtrack by Philip Glass, with original songs reflective of the era such as the works of Deep Purple, Pink Floyd, Fraternity of Man and John Lennon.

[8] Dan Jolin of the film magazine Empire gave Mr Nice three out of five stars, writing "A solid, often entertaining life-of-crimer which benefits from some stylistic touches and a faithful, convincing central performance.

"[11] Benjamin Mercer of The Village Voice also gave a polarized review, awarding the film 3.5 out of 5 stars, yet also claiming that the film gave him the impression of glorifying cannabis use, or at the very least, being a vehicle for the advocation of legalizing cannabis - "Though told here with appealing drollness, Marks' story makes an odd vessel for the filmmakers' casually advanced legalization arguments, what with its mischief making on the grandest scale possible.