Julia, celebrated for her stage performances and married to her producer-director (Jeremy Irons in a performance that’s just right) is becoming bored with her life. Suddenly she seizes the opportunity for a new escapade when Tom (Shaun Evans), a manipulative but attractive young American, makes a play for her.

An ambitious, conniving young actress, Avice Chrighton (Lucy Punch), gets in Julia’s way, in bed and on the stage, but Julia concocts her own devious method of dealing with the interloper, which makes for utter hilarity. Fueling everything is Bening’s flamboyant, multi-layered performance and Ronald Harwood’s adaptation that facilitates the elegant excursion into the period world of London theater.

I don’t usually like ghostly performances, but Michael Gambon is amusing as Jimmie Langton, the acting teacher Julia carries around in her consciousness. He frequently turns up to comment on her behavior or encourage her to remember his guidelines. The director handles these interruptions smoothly. Also credit fine actress Juliet Stevenson for her performance as Julia’s all around assistant. She brings a conspiratorial, winking tone to her work as helpmate.

The screenplay has its flaws. It is difficult to believe that given Julia’s long time platonic friendship with Lord Charles (Bruce Greenwood), she wouldn’t have realized a key aspect of his life much earlier.

Too much cannot be said extolling Bening’s flavorful, utterly captivating performance, and when she chooses to get even, there is a rollicking blowout in the form of stage shenanigans that should make any audience ecstatic with laughter. Then, in a subsequent solitary, silent moment in a restaurant after the show, the expressions that shift across her face tell so much about how she feels at that point in her life.