The birds were singing merrily, the sun was warm, and the Rowbarge Inn at Woolhampton, near Newbury, has been much improved. It was an ideal evening to see the water-borne Mikron Theatre Company as it moored up alongside the pub.

The show itself, however, sent a chilly shiver down the spine. Debtonation is the story of the ironically named Joy, and her husband Rod. Joy has arrived at the checkout of her local Marks & Spencer's food department. One by one, her credit cards are rejected. A manager is called - a mincing, slimy character who surely wouldn't last five minutes in the real M & S. Meanwhile, husband Rod, who suffers from a limp, encounters his former boss. "I'm very sorry for you," says the boss most insincerely, "but no, I won't take you back. Times are hard, and we can't carry passengers."

Richard Povall's script identifies a situation which is, of course, very real in 2008 Britain. But he doesn't seem to have quite decided whether to treat his story as a bittersweet comedy, a stage equivalent of a public information film, or both. Certainly he seems to have got it in for certain institutions - M & S's current food advertising, for instance, is sent up mercilessly, and a debt counsellor - part incompetent, part thoroughly patronising - is a disgrace to his profession. No doubt there really are people like that, but I can imagine anyone working at a Citizens Advice Bureau, for example, being absolutely horrified.

Fair's fair though, at the Woolhampton performance I saw, the storyline was followed with rapt attention, while the comparatively few outright laughs were eagerly seized upon. The excellent cast of four (Adrian Palmer, Erica Rogers, Gemma Ryan, and Daniel Wexler - pictured) are called upon to assume a multitude of different characters, which they achieve with conviction, even though the switches from high seriousness to comedy are sometimes awkward. The show is enhanced by Rebekah Hughes's music, while Erica Rogers is particularly impressive as fluffy Joy, a lady who eventually realises that having food on the table is more important than acquiring a bigger telly.

Debtonation can be seen next Tuesday, at the Queen's Head, Eynsham; on Thursday at the Boat Inn, Thrupp; on July 5 at Heyford Wharf; and on July 14 at Wharf House, Cropredy. Mikron's other show Fair Trade, the story of the Co-operative Movement, is at the Plough, Wolvercote Green, tonight; The Ferryman Inn, Bablock Hythe, on Sunday; at Thrupp on Wednesday, and at Cropredy on July 13.