[In the review below, Canby offers a laudatory assessment of The Cryptogram, extolling Mamet's use of language and disturbing dramatization of family life and "emotional games."]

The Cryptogram, David Mamet's radical, elliptical new work as both playwright and director, is not casually titled: it speaks in code.

The play is thick with spare Mamet language, which is delivered in such a relentless way that commonplace words take on an edge and a ferocity that have little to do with the meanings and emotions they usually evoke. The words sometimes punish. They also illuminate, creating a child's vision of the world with a poignancy seldom experienced in the contemporary theater.

At the end of the 75 intermission-free minutes, you may be moved and mesmerized, as I was. Or, like some others, you may be as ready to leap in front of a cruising taxi as to hail it. The Cryptogram is tough, but it rewards. The production, which opened last night at the Westside Theater Upstairs, is a virtual replica of the first-rate production staged by Mr. Mamet in February for the American Repertory Theater in Boston.

The Cryptogram is a family drama so pared down that it almost seems generic, though it's not. It's specific and idiosyncratic. There are three characters: John (Shelton Dane), a 10-year-old boy who is the son, Donny (Felicity Huffman), the mother and abandoned wife, and Del (Ed Begley Jr.), the unmarried family friend who represents Robert, the offstage father, husband and betrayer.

The year is said to be 1959, though the play appears to be taking place in the timelessness of a remembered childhood. Except for references to "the war," nothing attaches events to a particular period. Nor does anything in John Lee Beatty's scenic design suggest that these characters have much in the way of quotidian lives.

The single set looks stripped, devoid of details that might invite sentimental identification. It contains an inexpensive couch at center stage, a chair with an ottoman to the right, a rug on the floor and, at the back, a stairway to the second floor. There are no pictures, books or magazines, no windows or doors, no forgotten detritus of daily life.

Mr. Mamet is dealing in basics. It's as if we were seeing an American living room for the first time, possibly the barren truth behind the nothing décor of Father Knows Best. In the course of the play's three scenes, covering one month's time, this living room becomes an arena where John begins to grow up.

He's a bright child without being preternaturally precocious. He knows enough not to question the reasons for his father's departure, (Robert has fallen in love with another woman.) At the beginning of the play John and his father are planning to go on a camping trip the next day. After Robert vanishes, John seldom mentions him. The boy's on his own as his mother deals with her own abandonment.

Donny is not a cruel woman, but she's too involved with her own fury to pay much attention to John. Del, the feckless friend, is blamed for having been aware of Robert's affair, and for having provided the room where Robert and his new love would meet.

Such are the events of The Cryptogram, which is played out in a series of oblique encounters between the son and his mother, the mother and the best friend, and the best friend and the son. The dialogue is sometimes brutal in its banality. Del to Donny: "What are you going to do this weekend?" Donny: "This weekend?" Del: "Yes." Donny: "Well, I don't know." Del: "You don't know what you're doing this weekend." Donny: "I'm going to sit." Del: "To sit here." Donny: "Yes."

Much of this talk between the adults is simply sparring, not for time but to avoid facing truth. It also allows the voice of the boy to be heard with piercing, unexpected emotional impact. As he becomes increasingly aware of the collapse of the life he has known, he questions the truth of everything, the existence of things he has been told about but has never seen, including the cities on his globe. "Maybe," he says, "there's nothing on the thing that it is of," And, "We don't know what's real. All we do is say things."

These are not the sorts of philosophical questions that a distraught American mom wants to ponder. When John asks Donny if she ever wished that she could die, he briefly gets through to her. "Everyone has a story," she says. "This is yours. You're going to have to learn how to deal with it." Toward the end of the play, her patience, like Hitler's before he obliterated an entire country, is exhausted. She claims John has lied to her by not staying in bed. "I love you," she tells him, "but I can't like you."

The Cryptogram is a horror story that also appears to be one of Mr. Mamet's most personal plays. It's not about the sort of physical abuse we see in television docudramas, but about the high cost of the emotional games played in what are otherwise considered to be fairly well-adjusted families.

That's not easy to dramatize, Mr. Mamet's method is to create an insular world in which words are weapons that can maim. His direction is as cool and formal as his intricately designed dialogue. This is spoken by Ms. Huffman, Mr. Begley and Mr. Dane, the members of his extraordinary ensemble cast, with the sort of intense dispassion that allows us to understand the sense of things while being aware of every syllable. It's as if Mr. Mamet were deconstructing language to make us think more clearly.

I'm not sure that he entirely succeeds, but the effort is fascinating. The Cryptogram is a fine new American play.