The concluding weekend of performances at the Monteux Opera Festival in Hancock found David Katz’s hotshot singers thick in the melodies of “Tartuffe,” the Moliere farce about an opportunistic user, his codependent friend and the lessons they both learn. Because Katz and his crowd are dedicated to presenting lesser-known operas written in English, it seems there’s always a charming little gift waiting in the rustic concert hall tucked away among pines and birches of the Monteux School. So it’s not surprising that “Tartuffe,” with music and libretto by American composer Kirke Mechem, was a genuine gold mine.

Costumes, which the cast put together from personal collections, were as bright as Easter eggs against the richly dark set of art pieces and lush furniture. And there’s no underestimating the sprawling effect they erect in a rather small space. Part of that is the straightforward talent of the performers, and part is the user-friendly manner they have with the audience.

But the real strength of the Monteux troupe comes from the expertise of singers whose raison d’etre is opera and whose complementary skills blessedly include spirited theatrical abilities. Certainly the full cast of “Tartuffe” showed all that training listed in the program’s bios paid off. Among the 10 vibrant players, it would be hard to select a single talent as the shining star.

Nevertheless, baritone Ross Darlington, as Tartuffe, was frighteningly slimy with his low-down voice and even lower morals. T. Robert Morris, as his malleable friend, was intensely serious and powerful. Soprano Kathryn Hartgrove, as his wife, was vocally humorous and forceful. Kimberly Gratland’s unsullied soprano was enviable with every note.

Excellent performances were also given by Elizabeth Patches, John Murelle, Jason Scarcella and George Wolff (mostly for his goofball bits).

If pressed to choose a favorite, however, Cynthia Douglas, as the perspicacious maid, had a crystalline voice, an engaging presence and an expressive face that acted like a happy magnet to the audience. She has the type of onstage clarity that could easily convert any disaffected listener into an opera devotee.

Apparently, such conversions are exactly the thing music director David Katz is banking on with the Monteux Opera Festival. Although he and the deft collection of orchestral musicians sometimes overpowered the singers, the general effect of the show was that listeners couldn’t help but want more. Except for a concert Wednesday by the Bangor-based group Impromptu!, getting more means waiting until next August. But for opera lovers — or for anyone waiting for a conversion — it’s worth the wait.