Theatre: The Mysterious Mr Love Comedy Theatre, London

The Mysterious Mr Love, Karoline Leach's new play about a conman and his latest victim, is itself not above the odd spot of cheating. Affording Paul Nicholas the chance to flash his dodgy-charmer's grin, this two- hander, set in 1912, focuses on a professional fraud who, posing as a gentlemanly diplomat, hones in on vulnerable middle-aged spinsters and parts them from their savings via a quickie spurious wedding followed (for honour's sake "as a quid pro quo") by a quickie.

At first, Leach's play comes across as almost a send-up of the classic formula - unloved, gullible female, walking into bounder's trap - that's traditionally designed to bring a kind of sadistic sentimentality in the audience. The sheer speed here with which the 39-year-old, overweight, on-the-shelf millinery worker Adelaide Pinchin (Susan Penhaligon) falls for the blandishments of Love can't help but feel satirical.

The first twist comes on the honeymoon night in a dingy Weston-super- Mare hotel room. You may wonder why a man like Love doesn't just concede with relief when Ms Penhaligon's painfully self-conscious Adelaide asks not to be touched. But his puzzling sense of honour in this area pushes her into disclosing the cause of her reluctance: a history of eating disorders and low self-esteem linked to problems with a mocking, controlling father.

Before you know where you are, our confidence trickster has turned into a consciousness raiser, sensitively explaining the syndrome whereby fathers work off their own humiliations on their children and insisting that Adelaide assert herself. The man who had declared earlier that "whoever says women should have the vote wants his head testing" is now exposed as a bit of a closet proto-feminist.

You wait for the revelations about what it is in his own psychological background that gives him this fellow feeling with Adelaide, creating a conflict in him between his professional and his finer instincts. These eventually come, but not before further implausible manipulations of the material. Deducing Love's duplicity and intuiting that she might make a better man of him if his blarnying skills could be directed towards non-criminal ends, Adelaide switches, in a flash, to a woman with dreams of a Mayfair millinery empire. Offered a partnership that will combine her design flair and capital with his business savvy, Love declares, "I didn't know I'd married an entrepreneur." Neither did we.

Ms Penhaligon manages to give a genuinely touching performance, despite the fact that both her character and the play fail to add up properly. Called on in the second act to show us the damaged little boy inside the adult smoothie, the likeable Mr Nicholas is more wooden than wounded but the script does him no favours at this point. Bob Tomson's production is undeniably involving, though you always have the rather shamed sensation that your emotions are being toyed with rather than honourably exercised. Certainly, the last-minute twist suggests that where playing fast and loose with feelings is concerned, this play has nothing to learn from its hero.

To 25 Oct (0171-369 1731)