Marin Ireland’s Pre-Existing Condition is about the emotional aftermath of domestic violence. It is a quiet, unflashy play—75 minutes, sensitively directed by Maria Dizzia, with subtle performances from an ensemble of four—but no less devastating for its restraint. Lupita Nyong’o is outstanding as the protagonist, A: with fury, self-doubt, shame, and agony roiling beneath the surface, she strains at every moment to stay composed. The audience follows her through support groups, therapy, unhelpful family and friends, and the tentative possibility of letting herself trust again.