Roll up, roll up, for Anthony Neilson's mad freakshow of misery, first performed in 2002 and now revived by Headlong. A travelling Victorian spectacle complete with red velvet drapes, creaky stage illusions and a mysterious top-hatted impresario, it sometimes feels like the misbegotten bastard child resultant from an orgy of the talents of the League of Gentlemen,the Mighty Boosh and Derren Brown. Steve Marmion's production, performed by a nimble quartet led by Simon Kunz's mesmeric Gant needs more intensity and much more zany energy. And Neilson's writing sometimes slackens into self-indulgence. Yet the play oozes dark imagination.

Its first nasty treat is the sorry tale of “the pimple-faced girl”, condemned by dermal affliction to remain an object of disgust - until she discovers that squeezing her spots yields not pus but a perfect pearl. Giant singing pustules and a truly revolting sequence in which her jealous sister grows, and bursts, a forehead carbuncle so huge that she resembles Cyclops embellish a story of comic cruelty.

Lost love echoes mournfully through the gleeful grotesquerie. A tweedy gentleman explorer, distraught at his fiancée's death, submits to crude brain surgery at the hands of an Indian fakir; an enormous teddy bear tremulously recalls the day its infant owner viciously rejected it. Overseeing this compendium of melodrama and nightmarish nursery rhyme is Gant, whose half-crazed vision it all is, and in whose glittering eyes we glimpse despair deeper than that of any of the curiosities in his tawdry show.

As in The Wonderful World of Dissocia in 2004, Neilson traverses the disorientating hinterland of the unquiet psyche. This play touches on the melancholy at the heart of human existence, and on art's role as both its expression and as palliative - and though the drama meanders, its warped imagery and off-key lament for the lonely make a peculiarly compelling combination. Neilson holds up a fairground mirror that reveals the sadness and ugliness, the unlovely, fearful inner self that each of us struggles to keep hidden. The reflection is often frustratingly fragmented. But it's uncannily hard to look away.

Nuffield Theatre, Southampton (023- 8067 1771), to March 7; then touring to April 11 (www.headlongtheatre.co.uk)

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