Ariel Dorfman has described his new play Purgatorio as an intellectual and emotional sequel to Death and the Maiden. As in that 1991 piece, a prisoner is interrogated by an authority figure. But it’s far less clear cut, and far less clear altogether, than that ferociously gripping encounter between a rape and torture victim and her possible oppressor.

Purgatorio is one of those teasing cliff-hangers which isn’t really a thriller at all but operates by telling us far less than we want to know, and then making us guess anyway. An unnamed woman in black (Adjoa Andoh) is brandishing a knife in a bare room – a prison or an asylum? – at an unnamed doctor or supervisor (Patrick Baladi).

The woman comes from an island, was served by slaves, is known as a witch and has killed her husband’s new woman and her own children. Ah, she must be one of those Medea types, then. At this point, the light changes and the roles are switched: the woman dons the white coat and glasses while the man in black mulls over his chances of a new stab at life. He’s the object of the woman in the first scene’s fury and jealousy.

In the third scene, we pick up where the first scene left off, and the play winds up to a climax of recrimination, penitence and hopes for a new and better life second time around. We have been in purgatory all this time – in more ways than one, I’m afraid – and the discussion has boiled down to a theoretical discussion of guilt and revenge with the benefit of hindsight.

Coyly nestling in the published text’s afterword is the full explanation: the two characters are after-life versions of Jason and Medea. Stripped of its mythological resonance, and insufficiently relocated in any recognisable set of social circumstances, the play evaporates in dramatic intensity however much Adjoa Andoh, a powerful performer, turns up the volume.

Daniela Guerra’s production therefore stumbles between the two stools of allegorical significance and narrative energy. In seeking to extend the terms of reference of Death and the Maiden, Dorfman has in fact diminished them. I note that the play was given a reading in London in 2001 by Juliet Stevenson (the unforgettable victim in the 1991 play) and Simon Russell Beale. It has taken an awful long time not to sort out the inherent problems of a piece which seems to come from the head, not the heart.

- Michael Coveney