Lisa Ebersole’s Brother explores everything that can go wrong when a couple of sniping sisters invite a stranger into an impromptu late-night birthday party in their tiny New York apartment. The intimate play is full of unexpected disclosures and explosive confrontations. Tickets $15. 8 p.m. Thursday-Friday; through Aug. 6. The Elm, 220 Julia St., 218-0055;
www.elmtheatre.org