It’s patriarchy versus matriarchy in the house of Atreus. Manfred Trojahn’s 80-minute opera of 2011 revisits Euripides and tells the story of Orest’s murder of his mother, Klytaemnestra (who had his dad, Agamemnon, killed). Strauss, Berg, and Schoenberg are the spiritual fathers of this opera. Trojahn has tweaked the ending—and why not? —L.J.