The Duchess of Malfi, Royal & Derngate, Northampton

( ROBERT DAY)

Two corrupt brothers, a cardinal and a madman, prevent their sister, a widow, from remarrying by torturing and then killing her. The briefest summary of John Webster's Jacobean shocker never does justice to its genius and vivacity, but Laurie Sansom's imaginative revival does.

On a darkling stage, with a quintet of madrigal singers, and whispering walls hinting at Caravaggio paintings, we have dumb shows, stabbings, lust in the confessional box, night shrieks and lycanthropy, as the mad duke hunts badger by owl light and falls on his own shadow.

Even in this heavily cut (still nearly three-hour) version, there is the astounding poetry of jewels on the dung heap, dignity and shame, and shining virtue. Charlotte Emmerson plays the Duchess with a touching ferocity, bending the steward Antonio (Nick Blood) to her will, embracing death by strangling with a martyr's bravery: "Pull, and pull strongly, for your able strength must pull down heaven upon me."

With this play and The White Devil, Webster took tragedy to a new level in the psychology of evil, actual horror and callousness. And as the treacherous spy and informant, Bosola, David Caves undercuts his pantomime villainy with a steady Belfast accent; he's even more terrible for being so calmly spoken.

At first, there is too much confusion, too many unnecessary tableaux. But once the rhythm settles in, and the melody and dissonance of the Gesualdo madrigals covers the scene changes, the show's unstoppable.

Luke Neal is an athletic, psychotic Ferdinand, Daniel Fredenburgh chilling as the Cardinal, with Claire Dargo inventively doubling as the Cardinal's mistress and the loyal Cariola. Various lords are played, when needed, by the singers; "Moro, lasso" ("I die, alas") is the refrain that runs like a sweet poison through the final catastrophe.

To 30 October (01604 624811)