Susan and Darren, Lilian Baylis Studio, London<br/>La Danse, Frederick Wiseman, 159 mins (PG)

Curiosity may have killed the cat, but how much do we really want to know about others' lives?

Quarantine theatre company's Susan and Darren, "an event with dancing", pushes casual interest to the limit. While there's no doubt that everything you learn about the home life of gay, 30-year-old Darren Pritchard and his mother is the unvarnished truth, some of it is eye-wateringly humdrum.

The performing space is an empty square with audience on three sides, and a row of video screens on the fourth on which neighbours and friends of the pair intermittently appear, as if popping in for coffee. In the opening scene, Darren describes, in gesture and in fastidious verbal detail, his and Susan's Manchester home: the dimensions of its limed-oak furniture, the contents of the display cabinet, the position of the sofa and TV, even the gap in the laminate flooring that closes up when you kick it, only to open up a fissure elsewhere. Occasionally, Susan butts in to correct or add information. The sofa used to be blue, she tells us, until she bought some cream stretch covers.

This background as foreground clearly has a purpose. From the start, it places the characters in a precise demographic: not well-off, not sophisticated, more Argos than M&S. More importantly for the piece as theatre, it beckons the audience into the minutiae of the pair's lives, suggesting that more personal aspects are up for this level of dissection.

An earlier version of the show homed in on Darren's feelings on coming out to his mother (although she'd known he was gay all along). Now it focuses on his need to know about his father who – we learn as he gently lobs questions at Susan – died before Darren was born, "from having his head kicked in" during a late-night altercation at a taxi rank. "They could probably have shared that taxi," she muses.

Yet although Susan and Darren flirts with mortality, it's more concerned with acceptance and familial tenderness. There is no embarrassment when Darren lies with his head in Susan's lap, or when mother and son slow-dance to records in their living room – the contextualising has done its job.

The dance element takes other forms: matchstick-thin Darren moodily folding and refolding himself in contemporary-dance solos; Susan jiggling to a Diana Ross track; members of the audience joining the pair in a pre-rehearsed disco routine; most bizarrely, Darren performing a powerfully controlled pole dance to a choral mass. The point of the show isn't these performances, though. They're there because Susan and Darren love dancing. Likewise, the post-show finger buffet (prepared by some of the audience) is there because Susan likes entertaining. But it was the cheese-and-pineapple on sticks (shades of Abigail's Party) that finally did it for me, made me see the dismal class- patronage that (with the best will in the world, I'm sure) underlies this attempt at théâtre vérité. By the end, I felt I knew more than enough about this unusually co-dependent pair, and slightly grubby at having gawped into their world.

There is vérité of a different kind in Frederick Wiseman's film La Danse, in which he turns an unsentimental eye on the working life of the Paris Opera Ballet – without commentary or explanation. Institutions are the stock in trade of this prolific documentarist, resulting in 30 films that have dissected the modi operandi of everything from a zoo to an intensive care unit.

While many of these ventures have nailed organisations as dysfunctional or ineffective, in the case of France's premier classical dance outfit, Wiseman seems to have fallen headlong in love. Practically the only note of mild disquiet intrudes when the company's crumbly premises at the Palais Garnier get the decorators in. The painters, and briefly the janitor, are the only black faces you see.

Otherwise, Wiseman's camera is in thrall to the (all-French, all-white) dancers and their instructors. He seems particularly struck by the evanescence of the end product: all that toil for something there and gone on stage in a matter of minutes. But though the intensity of the camera's gaze is remarkable, the film's layering of one airless rehearsal after another (featuring no fewer than seven pieces from the 2008 season) is so dense it soon becomes dull.

'Susan and Darren': Curve, Leicester (0116 242 3569) 19-22 May; Arches, Glasgow (0141 565 1000) 26-28 May; Tobacco Factory, Bristol (0117 902 0344) 2-4 June; 'La Danse': on general release

Next Week:

Jenny Gilbert hones her translation skills for Babel – a joint venture by artist Antony Gormley and choreographer Sidi Larbi Cherkaoui