Arthur Dent (Martin Freeman) is rescued from the imminent destruction of the planet Earth by his best friend and – unbeknownst to Arthur – alien researcher Ford Prefect (Mos Def). Together they are thrown out of the airlock of a Vogon construction ship, rescued by Ford’s semi-cousin Zaphod Beeblebrox (Sam Rockwell) and Arthur’s former acquaintance Trillian (Zooey Deschanel), and sent on an adventure to the planet Magrothea to answer the ultimate question of live, the universe, and everything.

The Hitchhiker’s Guide to the Galaxy was a 1978 BBC radio serial. Written by Douglas Adams, its blend of science fiction and absurdist comedy was so popular with audiences that it soon became a 1979 novel, a 1981 television series, and a 1984 videogame. Four more novels followed, with a sixth volume in the air at the time that Douglas Adams suffered an untimely heart attack and died. It is a cornerstone of British science fiction and pop culture, and its fans are both numerous and ardent. Pretty much the only adaptation of Hitchhiker’s that eluded Adams during his lifetime was the feature film – and not for lack of trying. Despite numerous attempts to mount a big budget production from the 1980s to his death, the film simply failed to eventuate. It finally made it to the screen in 2005, four years after Adams had died, and helmed by music video director Garth Jennings.

It is a strange film. It is hard to imagine what anybody fresh to the story would have made of it. It jumps all over the place, throwing seemingly random and unconnected sequences up against one another and never pausing to catch a breath, get its bearing, or allow its audience time to re-orient themselves and have a hope of following it. At the same time it is an infuriating experience for many fans of the radio and television series or novel. It is not that the storyline has changed – the story changed subtly with every new adaptation – it is that the famous and beloved jokes and dialogue have all been weirdly shortened and truncated. Lines that used to sparkle now simply feel odd and out of place. The essential cadence that formed the humour of the piece has been terribly disrupted. For the viewer attached to the earlier iterations, it is difficult to engage with this new, peculiarly awkward version.

Adams was clearly keen to emulate Hollywood to the best of his ability – he was one of the writers of the screenplay before his death, and remained a credited producer. In the film he spins a love triangle out of what used to be one scene. He also gives the film an oddly artificial happy ending. It does give the film the tightest structure of any version of the story to date, but something innately wonderful is lost by embracing conventional storytelling instead of the rambling intellectual mess that used to be there.

Visually the film is mostly a treat. The production design is largely wonderful, particularly the beautifully realised and nicely loathsome Vogons, whose appearance employs practical costumes and masks instead of computer-generated effects. Other famous elements, including Marvin the Paranoid Android and the super-advanced computer Deep Thought, benefit from the freshness of design. Other creative choices feel oddly unsatisfying. Zaphod Beeblebrox, a character given two heads and three arms in the radio series as a throwaway gag, can finally be represented in a realistic fashion in a big-budget movie, and the additional head and limbs are weirdly hidden for the bulk of the film instead.

The film’s cast vary but are mostly effective. As Arthur Dent, Martin Freeman suffers from walking in radio and TV actor Simon Jones’ shadow. Adams wrote the role of Dent for Jones in the first place, and there is something about Freeman’s more energetic and youthful delivery that jars tonally with the character as previously presented. Mos Def fares much better, charting a fresh and original course as Ford and making the role very much his own. Sam Rockwell essentially plays Sam Rockwell, which is entertaining to an extent but loses the moments of calm that made Mark Wing-Davey’s original performances so entertaining. As Trillian Zooey Deschanel performs capably and brightly: the role as developed for the film is simultaneously larger than in previous versions – which is good – and a romantic cliche – which is not. Voiceover roles vary: both Alan Rickman’s Marvin and Helen Mirren’s Deep Thought feel a little phoned-in, while the League of Gentlemen (Mark Gatiss, Reece Shearsmith and Steve Pemberton) as the Vogons feels inspired.

Oddly the film works best when it is undertaking its own material. New sequences on the planets Viltvoodle 6 and Vogsphere are much stronger and funnier than any retread of the radio or television settings. There is certainly enough entertainment value to make it a worthwhile movie to watch, but one needs to be in a fairly forgiving mood if they’re a pre-existing fan. For now the 1981 television series remains far and away the best screen treatment of Adams’ creations, but the potential is still out there for a talented filmmaker to present something definitive. Jennings, for all the good elements he brings, does not come close to managing that.