Miss Sloane Jessica Chastain, Mark Strong, Gugu Mbatha-Raw. Directed by John Madden. Rated R. Opens Friday citywide.

Jessica Chastain’s title character opens Miss Sloane by giving a deeply cynical speech about the role of lobbyists in Washington, and the movie works hard to demonstrate how jaded it is about the way our government works. But as detached and amoral as Chastain’s Elizabeth Sloane purports to be, first-time screenwriter Jonathan Perera and director John Madden (Shakespeare in Love) also set her up as a crusading hero, beating the corrupt system at its own game. They get mixed results in their efforts to have it both ways.

Sloane quits her high-powered lobbying firm to join a small, scrappy organization dedicated to the passage of a gun-control bill, but her focus is on strategy and numbers, not on morality, and the movie’s many (many, many) plot twists are all about how Sloane out-maneuvers her opponents with tactics that eventually place her at the center of a Congressional ethics hearing (which frames the story in flash-forward). Chastain is fiercely compelling as the ruthless, hyper-intelligent Sloane, but the need to drop periodic narrative bombshells keeps her from building a fully realized character. The movie is so focused on blowing the audience’s mind that it eventually loses credibility, outsmarting itself even more effectively than its main character outsmarts her rivals.