The Houston Grand Opera gets it half-right with its latest pair of productions. The right part is its presentation of Benjamin Britten’s The Rape of Lucretia. The other part is Verdi’s La Traviata, which never quite achieves the potential of one of opera’s greatest hits.

The Rape of Lucretia is the final installment of Houston’s five-year Britten retrospective. Its story is an old one, dating back to Ovid and Livy in ancient Rome, through Shakespeare’s long poem The Rape of Lucrece and André Obey’s play Le Viol de Lucrèce to Britten’s and librettist Ronald Duncan’s opera.

The plot: A group of officers encamped outside Rome decide to go into the city to check on the fidelity of their wives. All of the wives except one, Lucretia, wife of Collatinus, are found to be unfaithful. One general, Junius, goads the king’s son, Tarquinius, into testing Lucretia’s fidelity himself. Tarquinius tries seduction, is rejected, and rapes Lucretia. She calls for Collatinus, tells him what happened, then commits suicide in shame although her husband is sympathetic to her. Junius sets out to lead a rebellion against the king, using the incident to rouse the mob.

Time is something of a problem in Britten’s and Duncan’s telling of the tale. The events portrayed supposedly happened about 500 B.C., but the two Britons present the story as a Christian morality tale, with two narrators making frequent reference to the suffering of Christ, the redemption of sin and the like.

Houston’s designers, Jean-Guy Lecat (set) and Anita Yavich (costumes), handle the time element by splitting the action. They devote most of the stage to Roman ruins (though this is supposed to be very early in the city’s history) and clothe most of the singers in ancient Roman costumes. Two characters, called “Male Chorus” and “Female Chorus” by Britten and Duncan, sit on either side of the stage and observe the action, coming out occasionally to comment. They are in modern dress.

Musically, Houston’s production worked beautifully on Sunday afternoon. Michelle DeYoung (Lucretia) and Anthony Dean Griffey (Male Chorus) were standouts, but the remainder of the cast were consistently impressive in other roles. These included Judith Forst and Lauren Snouffer as two servants, Jacques Imbrailo as Tarquinius, Ryan McKinny as Collatinus, Joshua Hopkins as Junius and Leah Crocetto as Female Chorus.

The Rape of Lucretia is a chamber opera with only 14 orchestral musicians. They, under the supervision of conductor Rory Macdonald, did a marvelous job of creating a mysterious atmosphere with sinister overtones. Britten was clearly a master of the orchestra.

Arin Arbus’ stage direction produced a consistently gripping drama.

Alas, the preceding evening’s Traviata was not so impressive. Albina Shagimuratova’s Violetta was vocally and dramatically admirable, as was Giovanni Meoni’s father Germont. But Chad Shelton’s Alfredo lacked the needed vocal robustness and something about his timbre grated on the ears. Not only that, but some members of the supporting cast sounded like singers in a university production.

It must be said that Shelton came in on short notice after the scheduled David Lomelí dropped out because of illness and Bryan Hymel sang the opening of the Traviata run.

Director Daniel Slater had some new ideas, some of them puzzling. He kept the chorus so tightly packed that some members of the audience may have felt a sympathetic sense of claustrophobia. An invention was the unsinging ghost of Violetta, who appeared occasionally to exchange or hand over white camellias to the living Violetta. At the end Violetta didn’t die; she just walked offstage through white curtains into what I assume was Heaven.

La Traviata closes out Sunday afternoon in Brown Theater of the Wortham Theater Center; the last performance of The Rape of Lucretia will be Saturday night.

Verdi’s Don Carlos and Donizetti’s Mary Stuart will round out the Houston season in April and May.