Has there ever been a more claustrophobic opera than Elektra, in which the children of Agamemnon finally avenge his murder at the hands of their mother? At the iconic Felsenreitschule—once the quarry for the builders of the nearby cathedral, later an outdoor equestrian arcade, now a covered mainstage for the Salzburg Festival—the survivors of the out-of-control House of Atreus have a whopping 40 meters of elbow room in which to conduct their business. The space will come in handy now that all must operate within personal six-foot bubbles. Ausrine Stundyte—very much on the rise—sings the punishing title role. The director Krzystof Warlikowski, whose intricately coordinated theatrical packages tend to float free of the content at hand, superintends the bloody goings on. Franz Welser-Möst, one of our foremost Straussians, conducts. —M.G.