Green Wing and Free Agents star Stephen Mangan is to play the lead role in BBC4s adaptation of the late Douglas Adams Dirk Gentlys Holistic Detective Agency. 　　Mangan will be joined by Darren Boyd as his sidekick Richard MacDuff and Cold Feet and Friends actor Helen Baxendale, as MacDuffs girlfriend Susan. 　　Adapted by the Bafta-winning writer Howard Overman – who is also behind Misfits, Vexed and Merlin – Dirk Gentlys Holistic Detective Agency follows the exploits of Adamss chaotic character as he uses his unusual methods to solve crimes. 　　Mangan said: "Ive been a fan of Douglas Adams ever since the Hitchhikers radio series which I used to record as a child and listen to over and over again in my bedroom. Its such a thrill to now be playing one of his brilliant characters. 　　"Dirk is a chaotic, anarchic force of nature with a totally unique take on the world. He is described as lazy, untidy, dismissive and unreliable. Ive absolutely no idea why they thought Id be right for the role." 　　The Dirk Gently books have formed the basis of a play and a BBC Radio 4 series but have never before been filmed for TV. 　　Adamss agent, Ed Victor, said: "For all the years I represented the late, great Douglas Adams, the most substantial frustration for both of us was that we couldnt get films made either of Hitchhiker or Dirk. 　　"Douglas once said, memorably, that getting a film made in Hollywood was like trying to cook a steak by having a bunch of people come into the room and breathe on it. Well, we did eventually get a film made in Hollywood of Hitchhiker and, tragically, Douglas didnt live to see it. Nor will he see this adaptation of Dirk – but its worth bearing in mind that Douglas always thought Dirk would make a better film than Hitchhiker and I feel sure that this new TV drama with a terrific script by Howard Overman will prove his point." 　　Shooting begins this week in Bristol on the 60-minute drama, which is being made by ITV Studioses in association with the Welded Tandem Picture Company. 　　The Dirk Gently production is to be directed by Damon Thomas – who also directed BBC4 drama The First Men in the Moon – and will air early next year.