LENOX -- In myth, Theseus was the warrior-hero who returned from obscurity to found Athens. In Handel's "Teseo," he's a love-smitten boy-hero back from battle but at the center of a love rectangle at court.
Or so he seemed in the Philharmonia Baroque Orchestra's minimally staged performance of the 1712 opera Thursday night at Tanglewood. On an autumnal evening, the singing was spectacular, the Ozawa Hall staging imaginative if limited, and the playing by the 31-member period-instrument orchestra, under Nicholas McGegan, vigorous, stylish and expressive. (But how did they manage to stay in tune in that chilly air?)
"Teseo," sad to say, is not top-drawer Handel. That isn't to say it doesn't contain some wonderful moments. The climactic scene when Teseo and his beloved Agilea -- she is also the object of King Egeo's desires -- are united and declare their love in flights of wild coloratura is Handel at his show-stopping best.
But the opera, telescoped here from five acts into two, proceeds largely in a series of numbers proclaiming love or revenge, or both. The plot is one of those "W loves X, who loves Y, who loves Z" affairs so dear to baroque composers' (and apparently their audiences') hearts.
To be brief about it: both Teseo and King Egeo love Agilea, but the sorceress Medea, to whom Egeo is engaged, also covets Teseo. Medea also knows, which others don't, that Egeo is Teseo's father. There is another couple, Arcas and Clizia, whose love entangles our heroes.
The Philharmonia Baroque, which hails from San Francisco, has been here before in a similar venture, Handel's "Orlando" in 2011. Again, the orchestra was seated in an oval, with McGegan inside at one end, presumably to better emulate the sound of a baroque opera orchestra. A pair of benches served as a set. The singers' garb was generally dark and vaguely modern, with Teseo gleaming in a white pants suit.
Originally a castrato role, Teseo was sung with agility, tonal splendor and dramatic firepower by soprano Amanda Forsythe, a star on the early-music scene. Soprano Amy Freston was her foil as the troubled Agilea.
Everything and everybody made way for the Medea, soprano Dominique Labelle, who hissed, cackled, brought down thunder and raised furies -- of both the human and hellish kind -- as she tormented the lovers. Soprano Celine Ricci mingled temper and humor as Clizia. Countertenor Drew Minter was a wimpy Egeo, and countertenor Robin Blaze a servile Arcas.
McGegan conducted firmly -- more than that, enthusiastically -- and there were some laugh-out-loud comic bits, such as the discovery by Egeo and Medea that, despite their betrothal, they didn't love each other. There were also some irresistibly fine solos by oboist Marc Schachman and flutists Stephen Schultz and Mindy Rosenfeld. And with the lovers united and Medea vanquished, the classical season in Ozawa Hall ended.