Chaos reigns in this strange, funny and amiably anarchic mockumentary about dirty tricks in the cutthroat world of competitive marrow-growing, written and co-directed by film-maker Brook Driver. Maybe the script could have gone through another couple of drafts, but that might have removed some of the flavour. As it is, it feels like Thomas Pynchon had emailed Ricky Gervais an idea he’d had for a British comedy, and the result certainly has some laughs.

Jo Hartley (a stalwart of Shane Meadows’s movies Dead Man’s Shoes and This Is England) is Caroline, a marrow-grower and a divorcee who pretends her ex-husband is dead and is now in a kind of NSA relationship with her needy neighbour Willy (Celyn Jones); they are both mates with conspiracy theorist and fanatically competitive prize-veg enthusiast Paul (Richard Lumsden). When Caroline’s marrow is disqualified one year for having a hairline crack and then her other marrow (called Ricky Hatton because it’s such a fighter) is stolen from her garden greenhouse by masked raiders, Caroline sets out on a desperately dangerous quest to find what on earth is happening. But this involves hiring a supremely louche pair of private detectives: Louise (Aisling Bea) and Lawrence (Ray Fearon) a married couple who also run swinging parties that Caroline has attended.

There’s a fair bit of amusement and ironic drollery to be had here, though also a few moments when the film loses momentum and focus and you’re allowed to wonder where we’re going with it. No less a talent than Alice Lowe appears in such a mystifyingly tiny role that I wondered if we had lost some of her character in the edit. Fay Ripley has a funny cameo as a rival grower who earnestly describes two competitors in the marrow world as “the Muhammad Ali and Cassius Clay of the big veg world – big rivals!” The film doesn’t quite develop and absorb all of its funny ideas, but there’s plenty of taste and texture.

• Swede Caroline is in UK cinemas from 19 April.