Capella de'Turchini / Antonio Florio CAVALLI Statira

Though it has its flaws, this is a hugely important issue that adds immeasurably to our understanding of Pietro Francesco Cavalli, the dominant Italian opera composer of the second half of the 17th century. His music fell out of fashion after his death, and its rediscovery, which began with Glyndebourne's productions of L'Ormindo and La Calisto in the 1960s, has been a slow process. This recording of Statira, first performed in Venice in 1656, cannot help but change our views of his output as a whole, since it reveals a dark side to Cavalli hitherto ignored.

It begins in familiar territory. The plot is rooted in one of those complex, cross-dressing tangles - quintessentially Cavalli - complete with an emphasis on bisexuality as fundamental to human nature, something that made the composer unperformable for centuries. Statira, daughter of King Darius of Persia, is in love with Cloridaspe, king of Arabia. There are, of course, complications. Usimano, an Egyptian prince, is also besotted with Statira; in order to pursue her, he has disguised himself as a woman and is now employed as her lady-in-waiting. "Ermosilla", as he calls himself, attracts men like a magnet, including Cloridaspe's brutal sidekick Nicarco and his manservant Vaffrino.

Anyone expecting this situation to resolve itself serenely after the fashion of Calisto, however, is in for a shock, for the opera's subject is actually the relationship between sex and war. The men are members of a military alliance that is in the process of flattening Armenia. whether it holds or not depends on the shifting sexual allegiances back home. Once Usimano's guise has been penetrated, Statira becomes a bargaining tool between themen, who demand her favours in exchange for military service to her father. A conventionally happy ending doesn't alleviate the resultant nastiness.

Stylistically, the score blends familiar Cavalli with startlingly new elements. Cloridaspe and Usimano are both played by women, which means there are plenty of his sexy trademark duets for twining female voices. Instead of advancing the action with extended recitative dialogues as in La Calisto, however, Statira often proceeds by way of successive monologues that swing from recitative to arioso and back. As Statira becomes a pawn in a man's world, her growing anguish is mirrored in arias of ever-increasing size and difficulty. Cavalli is frequently cited as the link between Monteverdi and Handel; his pivotal nature has never been more apparent than here.

Conducting his own Naples-based period band, the Cappella de' Turchini, Antonio Florio's performance has great clout. Cavalli never wrote out the orchestration in full - in the 17th century, much of it would have been improvised in performance - and this performing edition is Florio's own. It's very stark, with dry strings and sparsely deployed woodwind and brass, far removed from the smoothness of Raymond Leppard's editions or the jazzy flamboyance of René Jacobs.

The singing, however, is uneven. Clarity of diction sometimes takes precedence over beauty of line. Dionisia di Vico's Cloridaspe reveals some ungainly register breaks, and Giuseppe Naviglio's Nicarco isn't quite dangerous enough. On the plus side, however, there's Rosario Totaro's funny, cynical Vaffrino, Maria Ercolano's complex, vibrant Usimano and, above all, Roberta Invernizzi's Statira, miraculously fusing sound with sense in even the most taxing bravura passages. This is a restoration of a lost masterpiece by one of opera's greats, and you need to hear it. (Tim Ashley / The Guardian)