Pia de' Tolomei was a 13th-century Sienese noblewoman who came to an unpleasant end. Her husband Nello, anxious to be rid of her, immured her in a castle in the middle of a malarial swamp, hoping she would contract the disease. When its ravages failed to kill her, he had her poisoned. Her story, told by Dante in the Purgatorio, also forms the basis of this Donizetti opera, premiered in 1837 and now revived in concert by Opera Rara.

It proves to be a fascinating, flawed work, full of anger and sadness. Pia and Nello are the victims of a conspiracy. He believes an accusation of adultery, brought by one Ghino, whose attentions Pia has rejected. She has indeed been secretly meeting a stranger - but he proves to be her brother, Rodrigo, who is Nello's opponent in a civil war that is destroying Italy as well as Pia's family.

The opera is hampered by an overlong exposition, though once it is past the halfway mark, it exerts a vice-like grip. Malarial fever is Donizetti's cue to give Pia one of his most disturbing mad scenes. One scene in the climactic sequence, however - in which Pia effects Ghino's moral redemption in a duet - so closely resembles the confrontation between Violetta and Germont in La Traviata that one can only assume Verdi took it as his model.

The performance also had its flaws. David Parry's conducting was occasionally overemphatic. Roberto Servile's Nello was uninvolved, while Bruce Ford's Ghino revealed that his voice has lost its former beauty. The great performance, however, came from Majella Cullagh in the title role - technically staggering, pushing herself to her expressive limits in order to convey Pia's emotional and moral agony. She has the potential to become one of the great bel canto divas of our time.