Debuting at Islington's Kings Head Theatre last year as a lunchtime show, Gertrude's Secret is a series of stand-alone monologues, written by Benedick West, in which each lonely character reveals a dark secret to the audience.

Unfortunately, two of the best-written and performed vignettes - Felicity Duncan's accounts clerk Maureen, hopelessly besotted with a fellow commuter, and Christopher Knott portraying cancer sufferer Alexander with an almost unbearable poignancy - come at the start. After that, it feels like the audience is trapped in a mire of misery, the characters putting their pain on show like beggars displaying mutilation.

West's writing is often inconsequential, with stories tailing off rather than concluding. There are some laughs, but they're frequently uneasy, and even the excellent Prunella Scales (West's cousin) has difficulty balancing humour and pathos in her role as Gertrude, awaiting a birthday telephone call, although 13-year-old Jerusha West (the author's daughter) hits exactly the right note as a confiding prepubescent, innocently unaware that she is in terrible danger.

Ann Micklethwaite's gobby Northern chav Tina, cheerfully making the most of life on the dole, ends the performance in more upbeat fashion, but overall, this is a quietly disturbing evening.

• Until 11 Feb, 27 New End, London NW3 1JD (0870 033 2733, www.newendtheatre.co.uk), Tues-Sat 7.30pm, Sat-Sun 3.30pm, £18.00, concs £15.00. Tube: Hampstead.