Defeated by Pompey and sending a report of his own death, Mitridate returns to his kingdom to find that his two sons are in love with Aspasia, his bride-to-be. Farnace, the elder, rejects Ismene, to whom he is betrothed, and plots against his father; Sifare’s love for Aspasia is returned. Mitridate imprisons both sons but they rally to his aid when the Romans invade. Mortally wounded, the king blesses the union of Sifare and forgives a remorseful Farnace.

Mitridate was composed by the 14-year-old Mozart for the ducal theatre in Milan. It’s an old-fashioned opera seria, complete with a (more-or-less) happy ending. Mozart rose to the challenge with music of an astonishing power and beauty, albeit at a very leisurely pace. This production gets off to a rocky start. A group of actors assembles; there are chairs and a trestle table; breakfast is taken. A boy reads aloud the first couplet from Mithridate, the tragedy by Racine on which the opera is based. Then, reverting to Italian but still reading from the paperback, Patricia Petibon/Aspasia launches on a rewritten version of Mozart’s recitative; she is still holding the book in the ensuing aria. You fear that the whole opera is going to be sent up, but once the adults have raided the dressing-up basket, the real drama takes over.

There are several things to which one might take exception: Farnace, who has not been in battle, has his arm in a sling, with a bloodied sleeve; Mitridate looks very unregal in his belted raincoat. However, Clément Hervieu-Léger, an actor and director from the Comédie-Française, gets vivid acting from his cast. The plain setting forces one to concentrate on the emotions of the characters. Musically, everything is first-rate. Michael Spyres negotiates the wide leaps of his entrance aria with ease. Patricia Petibon is accomplished in the coloratura and intense when she addresses the shades of Elysium. Sabine Devieilhe’s lighter soprano is perfect for Ismene. The roles of Sifare and Farnace were written for castratos. Myrtò Papatanasiu, abetted by a fine horn obbligato from Jeroen Billiet, manages the long lines of ‘Lungi da te’ wonderfully well, while Christophe Dumaux produces a stream of golden tone in his repentance scene.

Emmanuelle Haïm’s tempos are ideal and Le Concert d’Astrée play impeccably. Ultimately, though, I wouldn’t recommend this over Graham Vick’s Covent Garden production (being revived this summer with, as it happens, Michael Spyres): reducing the original three acts to two makes for an over-long first half and spoils the Act 2 curtain, where Aspasia and Sifare have – the brief final Coro aside – the only ensemble in the entire opera.