Keenan-Bolger and Parsons are very good indeed in Mother Play, but there’s no question to whom it belongs. Lange is magnificent, especially in this production’s most moving scene: a long passage that the script calls the Phyllis Ballet. Phyllis is alone onstage, because she has pushed everyone away. There is no dialogue, because she has no one to talk to. She stares out motionless at the audience for a discomfiting amount of time, letting us project onto her face like an actress in a film; then, in a silky magenta robe, she enacts a kind of sad silent comedy, setting a dignified dinner for herself and dousing her food in hot sauce. She has fallen down the well of loneliness. Bringing decades of experience to bear, Lange is riveting—and so, by extension, is Phyllis.