Handel’s first opera, Almira (January 1705), is the only one of his juvenile works for Hamburg’s Gänsemarkt theatre that survives in almost complete form. Based indirectly on an old Venetian opera (1691), the drama is set in medieval Valladolid: newly crowned Queen Almira of Castile appoints her guardian Consalvo as her advisor and is expected to marry one of his sons, but she is secretly in love with the foundling Fernando. There is little prize for guessing that Fernando turns out to be Consalvo’s long-lost son (thought to have drowned in infancy), but working this out takes about four hours of complicated entanglements and often daftly impetuous misunderstandings – the happy ending requires a triple wedding.

The inexperienced 19-year-old’s score is a compound of Italian, German and French elements that was customary in Hamburg productions of the period: 52 arias are predominantly very short (about a third accompanied only by continuo), yet 15 of them have Italian texts. All three acts contain French-style dances, and the first few scenes of Act 3 are an entrée for dancing Europeans, Africans, Asians (whose saraband has more than a whiff of ‘Lascia ch’io pianga’) and Jesters.

Boston Early Music Festival’s concertmaster Robert Mealy and artistic co-directors Paul O’Dette and Stephen Stubbs prepared their own performing edition, reconstructed a few missing portions of music, and provided a persuasive orchestration for Almira’s ‘Ingrato, spietato’ (its voice and bass lines rediscovered in 2004). There are distinctive differences from the opera’s only previous recording (also on CPO), such as the Bostonians’ artistic licence to use harp continuo (applied copiously in continuo arias) and occasional sprinkles of percussion; very loud castanets besmirch the ‘Spanish’ saraband in Act 1. A hurdy-gurdy drone during the comic servant Tabarco’s turn as Folly in the Act 3 entrée is a suitable solution to the stage direction mentioning ‘Sackpfeiffe’.

Almira’s heartbroken reaction to Fernando’s perceived infidelity (‘Geloso tormento’) is a sensitive dialogue between Emőke Baráth and plaintive solo oboe, accompanied by tense pulsing strings. Elsewhere, Baráth’s supple coloratura is shown off admirably and takes in a few light throwaway top Cs. Indeed, no other Handel score has so many written top Cs, and the majority are dispatched with quicksilver deftness by Amanda Forsythe’s Edilia. Her entrance is a lovely pastoral with recorders and concertante violins in its middle section, swapping over to oboes in the short modified da capo, whereas several tempestuous arias showcase Forsythe’s agility and finesse – and foreshadow cantatas Handel would write in Rome a few years later.

Colin Balzer’s Fernando is equally adept at ardent, shapely singing and brawnier heroism. His Act 3 prison scene charts an emotional trajectory through a turbulent F minor aria of distress, an accompanied recitative, a gentle lament expressing eternal love for Almira and their giddy (short) duet of reconciliation. Zachary Wilder’s Osman displays superb technical control and smooth delivery of fiendish coloratura. He ends up hitched to Bellante, sung sweetly by Teresa Wakim (albeit with a touch of unsteadiness). Jesse Blumberg contributes warm-toned seductive singing as Raymondo (the Moorish king of Mauretania), Christian Immler’s intelligent singing makes more out of Consalvo than Handel’s perfunctory music suggests, and Jan Kobow’s comic timing and inflection are spot on as Tabarco.

The only cut is a Rondeau omitted from Act 1 scene 11. This is a revelatory milestone in resuscitating the artistic currency of Handel’s operatic debut.