The setting is a homey, if spare, living room; but nothing much else about David Mamet's play The Cryptogram, which opened in Boston last week in a production by the American Repertory Theatre, is very reassuring. A young boy waits eagerly for his father to come home; he never does. The boy's mother is first heard offstage, breaking a teapot. A gay friend of the family's dissolves in guilt over a betrayal. No one seems capable of finishing a sentence or answering a question directly. There is vaguely unsettling talk about a combat knife. The boy can't sleep.
After an uncharacteristic...