Fans of Douglas Adams' two most celebrated creations, The Hitchhiker's Guide to the Galaxy and Dirk Gently's Holistic Detective Agency, won't be surprised to learn that this isn't a conventional edition of the LWT's august arts strand The South Bank Show.

Yes, there's the usual face-to-face interview with host Melvyn Bragg, plus interventions from collaborators, friends and admirers, including Stephen Fry and John Lloyd (Adams' co-author on the cult book 'The Meaning of Liff'), as well as his admirably patient publisher. But the remainder of the programme bends itself to its subject's witty, inventive and very idiosyncratic imagination, as characters from his work - hapless Galactic hitchhikers Arthur Dent (Simon Jones) and Ford Prefect (David , Marvin the Paranoid Android (Stephen Moore) and the Electric Monk (Paul Shearer) - converge on Adams' Islington flat, where they learn the shocking truth of their existence.

The justification for the author getting the Bragg treatment is the arrival of 'Mostly Harmless', billed as "The fifth book in the increasingly inaccurately named Hitchhiker's Trilogy". In a candid interview rich in characteristically leftfield insights, Adams expounds on science, religion, the human condition and rhinoceros mucus, and his own chronic procrastination.

Learn how sumo wrestling inspired the Infinite Improbability Drive, and how a brief stint working security for visiting Arab dignitaries planted the idea of sentient technology, and how the Electric Monk was an expression of Adams' radical atheism. And if that's not enough, there's behind-the-scenes footage of the recording of the original Hitchhiker's radio series and a droll dramatisation of Dirk Gently's Holistic Detective Agency (with Michael Bywater in the title role) - a full 18 years before the BBC got around to televising it.