On April 3, 1968, in Memphis, Tenn., Martin Luther King Jr. addressed a rally in support of black public works employees, delivering his famous “I’ve Been to the Mountaintop” address at Mason Temple. That night, he stayed in Room 306 of the Lorraine Motel. The next day, he was assassinated on the balcony of that motel.

Katori Hall’s intriguing play about the night before that tragic event, “The Mountaintop,” is playing at Arena Stage, directed ably by Robert O’Hara.