According to a lost epic, the Amazon Penthesilea was killed by Achilles who fell in love with her on removing her helmet (and some say sexually violating her corpse). French composer Pascal Dusapin’s eighth opera (2015) is based on an obscure variant reading in an 1808 drama by Heinrich von Kleist. An exploration of carnal frenzy that Goethe pronounced “unplayable,” it reads today as a pathological battle of the sexes. Kleist reverses the ending with Achilles killed and the deranged Penthesilea...