In Chapter 18 of Genesis, the elderly Abraham and his wife, Sarah, provide hospitality to three mysterious travelers. Having gratefully received food and drink, the visitors (avenging angels) tell Abraham that his previously barren Sarah will soon bear a son. She laughs at the prophecy, but it will come to pass with the birth of Isaac. The visitors have come to wreak divine vengeance on the sinful nearby twin towns of Sodom and Gomorrah. Abraham shows them the way, but then engages in an impassioned dialogue with God, begging for clemency, arguing that the cities should be spared for the sake of the few righteous people — even if only 10 — living there.

“What interested me about this story,” MacMillan said recently in a phone interview from his “mild and snowy” native Glasgow, “is that it’s about ordinary people asking the divine to be clement, the opposite from what would be expected. The three visitors are unmerciful, but also representatives of the divine. So it makes us think about the relationship between the human and divine.”

First performed at the Linbury Studio Theatre of London’s Royal Opera House in May 2011, “Clemency” will be receiving its North American premiere in a new BLO production directed by Andrew Eggert opening on Feb. 6 for four performances held, like all the productions in BLO’s Opera Annex series, in a nontraditional venue. This time it is the Artists for Humanity EpiCenter in South Boston. BLO co-commissioned the opera along with Britain’s Royal Opera House, Scottish Opera, and the Britten Sinfonia.

Composed in one act and lasting about 50 minutes, “Clemency” was presented alone in London, and at Scottish Opera last summer. For the BLO production, however, music director David Angus decided to pair it with an opening dramatization of a song by Franz Schubert, “Hagar’s Lament,” a setting of a text by Clemens August Schucking. This is Schubert’s first published song, composed in 1811, when he was only 14. A substantial dramatic cantata originally scored for voice and piano, it focuses on what happens in Genesis just before the action described in “Clemency.” Sarah’s maid Hagar bore a son, Ishmael, by Abraham at the urging of Sarah, who had been unable to conceive. But later Sarah expels Hagar and the infant Ishmael into the wilderness, where Hagar laments her bitter fate to God.

Maestro Angus, who will conduct, has orchestrated some portions of “Hagar's Lament” for the same small string orchestra used in “Clemency.” The two pieces will be staged without a break, as one integrated theatrical whole, for six singers and string orchestra. Soprano Christine Abraham sings the role of Sarah, with baritone David Kravitz as Abraham and Michelle Trainor as Hagar. The roles of the three “travelers” are sung by male voices: two tenors (Neal Ferreira and Samuel Levine), and a baritone (David McFerrin).

Boston audiences know the deeply spiritual, dramatic, often ecstatic music of James MacMillan — considered by many to be today’s leading British composer — from several recent performances by the Boston Symphony Orchestra. In 2010, the BSO gave the American premiere of MacMillan’s oratorio “St. John Passion” (a BSO co-commission), and earlier this season played the orchestral interludes from his 2006 opera, “The Sacrifice,” on Welsh folk legends, also adapted by Symmons Roberts.

It was, in fact, when MacMillan came to Boston for the “St. John Passion” performances that the idea of including BLO in the commissioning of “Clemency” occurred. As it happens, Nicholas Russell, BLO’s current director of artistic operations, is also a Scot from Glasgow (a fellow Glaswegian) who formerly worked at the Scottish Opera and has known MacMillan (“Jimmy”) for years. “We even lived on the same street in Glasgow,” Russell said recently, “and I once commissioned a short anthem from him for my father's birthday.”