A wounded soldier’s leg is amputated in the first scene of “The Whipping Man,” which opened last Friday evening in a powerful staging at the Black Rep.

As harrowing as the amputation is, the second act of the play by Matthew Lopez, includes an even more memorable scene. It is a seder held in Richmond, Va., in April 1865, just days after the end of the Civil War.

This seder is compelling because of the participants and the occasion. The setting is the devastated home of a wealthy Jewish family. Two of the three men at the service had been slaves in this household and were brought up as Jews. For them, the seder is a double observance. They are celebrating not only the freeing of the ancient Israelites but also their own liberation from slavery.

The third man at the seder is Caleb DeLeon, an officer in the Confederate army. At the start of the play, he collapses after hobbling into the ruins of his family’s once grand house. Justin Ivan Brown convincingly portrays Caleb’s physical and mental anguish.

Caleb is found by Simon, a long-time slave of the DeLeons who is guarding the family home. Simon is awaiting the return of his wife and daughter, who accompanied Caleb’s father when he fled Richmond.

Simon is the one who recognizes that Caleb’s wounded leg is gangrenous and has to come off. Simon’s loyalty to the DeLeons is clear in his concern for Caleb, but Simon is no longer content with being told what to do. Actor Ron Himes establishes Simon as the play’s moral compass as he and his former master work out a new relationship.

The last character on the scene is John, another former slave of the DeLeons, who has come from looting nearby houses. He enters with a hood over his head to frighten his former master. John’s new-found freedom has fed his longstanding rebellious streak. He has made many trips to the Whipping Man, the person hired to punish misbehaving slaves. Ronald L. Conner has played defiant characters at the Black Rep before, and once again he performs with formidable intensity.

John’s swagger turns to alarm when he hears that someone has been looking for him. John is clearly hiding something. So is Caleb, who resists answering questions about why he did not seek treatment for his wound.

Even more secrets are revealed at the end of the seder, bringing the play to an unexpected but satisfying conclusion. The seder itself is an extraordinary event. Himes projects inspiring authority as Simon leads the service and underscores the relevance of the ceremony to what has just happened in America. The singing of the spiritual, “Go Down, Moses,” is especially moving.

The bleakness of the setting is vividly conveyed by Tim Case’s set, Mark Wilson’s lighting, Lou Bird’s costumes and Robin Weatherall’s sound. The amputation and the seder are as striking as they need to be under the direction of Ed Smith, but he is equally attentive to the subtleties of character and plot development that make the play a satisfying whole.