While I was growing up, my best friend's mother had a fridge magnet that read: "A tidy house is the sign of an untidy mind." It's something I always bring up when my partner sees the state I leave my own bedroom in. It's also perhaps the message of this week's big play in town, although you probably would not guess it, buried as it is, in a mire of middle-brow sentiment and half-baked character observations.

The Clean House is a gentle comedy, lightly dusted with elements of tragedy, fantasy, whimsy and melodrama. It tells the tale of Mathilde (Natalia Tena), a 20-something Brazilian, who comes to work as a cleaner at a house belonging to a pair of affluent doctors (Patricia Hodge and Oliver Cotton). However, she would rather be telling jokes than cleaning, and the state of the place is soon recognised by frequent visitor, and the sister of the lady of the house, Virginia (Joanna McCallum). Virginia, won over by Mathilde's spirit and her warmth, offers to help clean. However, they both soon come across some unpleasant secrets that only someone privy to the inner workings of a home could find out.

After a bouncy first half, the play becomes considerably more serious. Surprisingly, this comes as something of a relief, although the change is mishandled considerably. Although light and fun, the first half is completely lacking in substance, and occasionally its treatment of the source material seems frustratingly flippant and glib. There is an almost shocking lack of balance between the play's halves, as the writer clearly struggles to change tone to give the piece much-needed gravitas, while keeping intact the fragile eggshells of characters she has created.

What happens is that there are a series of touching moments and wonderful pieces of dialogue, but it all amounts to very little. Some nice observations and metaphors about cleaning one's house in relation to how you live your life are frankly not good enough to give weight to a flimsy set up, and even flimsier characters.

The considerable acting talent does its very best, and the whole thing is mercifully short, but you do wonder what the point of it all was. The play continues until tomorrow at the Oxford Playhouse.