This dramatic marathon is Eugene O'Neill's take on the Oresteia, served up with a hefty wedge of Freud and a slice of old-fashioned melodrama on the side. O'Neill's vision - which contains enough murder, adultery, suicide and incest to keep a soap opera producer happy for months - offers us a world of family horror as id and thanatos collide on the way to the inevitably doomed conclusion.

Mourning Becomes Electra is even darker than Aeschylus' original. Here, there's no redemption for Orestes; the play unfolds adding horror to horror. But Howard Davies' production never slips into histrionics and concentrates on sexual desire and guilt that lies at the heart of this unremitting examination of family politics.

O'Neill's version of Clytaemnestra, Christine Mannon, is more one-dimensional than the Greek original. It's too easy to present her as an unfeeling, murderous adulteress. But, in an outstanding performance, Helen Mirren breathes life into the character.

We see a woman terrified at the thought of her beauty fading, her voice choking when she tries to imagine herself old and ugly, and driven by jealousy of her daughter whom she knows is going to grow up to be the desired one. And Mirren's anguished, mocking cry of "life" just before going into the house to shoot herself is a chilling moment, the word left hanging as an admonishment to those still living.

Eve Best as Lavinia, the Electra of the title, is nearly as good. She struggles with the American accent at times, lending a strange quality to her speech, but she copes admirably with the huge demands of the role. She's required to capture desire and hatred, guilt and jealousy, often at the same time. Best succeeds in giving us a woman who's seemingly always on the verge of bursting into life but never really managing it. While her desire for her father is played down, her secret passion for Brant, her mother's lover is very much to the fore - kissing his corpse before fleeing the murder scene.

For me, the best performance of the night, however, comes from Paul Hilton as Orin, the Orestes figure. He grasps the decay at the heart of the Mannon heritage and is compelling from the moment he first appears on stage. We fully comprehend that this self-mocking and troubled man is destined to be the nemesis of his doomed family.

There are strong performances elsewhere, too: from Paul McGann as the doomed Brant, from Clarke Peters as the Chorus-like figure of the gardener, and from Rebecca Johnson and Dominic Rowan, who manage to flesh out the characters of Hazel and Peter Niles when they could so easily be mere cyphers - the wholesome flipside of the corrupted Lavinia and Orin.

Bob Crowley's set admirably complements Davies' vision of the play - complete with a dramatic scenery transformation halfway through. This is a superbly realised production, draining for the audience perhaps, but a salutary reminder of the darkness that lies at the heart of many families - and just in time for Christmas too.

- Maxwell Cooter