Randa Rouweyha and Robert Harrelson perform in "Fidelio" at the Atlas Performing Arts Center. (Rx Loft Photography)

The In Series tackled an ambitious project in mounting a fully staged production of Beethoven’s only opera, “Fidelio,” which opened Saturday afternoon at the Atlas Performing Arts Center.

Nick Olcott, the thoughtful director, created a free but stylish English adaptation of the libretto that credibly relocated the action from late-18th-century Spain to a 20th-century South American dictatorship. Music director Stanley Thurston conducted a pared-down orchestra of 14 well-prepared players. If there were occasional ensemble discrepancies, these were mostly between stage and pit. Hearing the famous overture played by a chamber-size ensemble was but one highlight of a generally musically taut production.

Sarah Greenspan brought stamina and a big voice to the role of Leonora/Fidelio, one of the more challenging of the soprano repertory. Joe Haughton was effective as her imprisoned husband, Florestán, and Robert Harrelson’s Rocco, the jailer, was beautifully sung. The best acting was by Randa Rouweyha, who negotiated the florid part of Marcelita with aplomb, and by Jesús Daniel Hernández as Joaquino, Marcelita’s would-be suitor. The male chorus of prisoners emerging from their subterranean cells into the light of day was powerfully sung and deeply moving.

Elizabeth McFadden’s set, Donna Breslin’s costumes and the lighting design of Marianne Meadows all contributed to an unusually integrated production.

As happens so often in opera, the whole is significantly more than the sum of its parts. Part of the afternoon’s pleasure was seeing a small arts organization like In Series stretch to achieve considerable success with a canonical masterpiece and all the heightened expectations such a work entails. In an age when opera direction reflexively strains toward contemporary relevance, this updating of “Fidelio” seemed unostentatiously effortless and apt. And at the end of a week that saw appalling bloodshed in Florida and the slaying of a member of Britain’s Parliament, there can be no question that this encounter with Beethoven’s portrayal of human devotion and the struggle against oppression was profoundly restorative.

The In Series production of “Fidelio” has performances Saturday and Sunday.