Madeleine Elizabeth Sloane (Jessica Chastain), a high-level, pill-popping, cutthroat lobbyist in Washington, D.C., is described by a colleague as a real "piece of work" in this scathing and timely political thriller. And that's an understatement: Sloane's only goal is to win, and if that means she has to manipulate, belittle, embarrass, and run roughshod over people -- even those closest to her -- then so be it. "The end is my concern," she says, and achieving that triumphant outcome always justifies the means. Always.The film begins with a congressional hearing, led by Sen. Ronald Sperling (a tough John Lithgow), that is investigating some of Sloane's alleged unethical practices (which supposedly include espionage). She pleads the Fifth to every question. The story then jumps back several months to Sloane's time working for a top-tier lobbying firm, as the movie explains how she got herself hauled in front of the committee. Her boss (Sam Waterston) wants her to lobby on behalf of an NRA-like advocacy group that's trying to persuade women to join their side in defeating proposed gun-control legislation. Although Sloane's morals are dubious at best, there are causes she believes in and gun control is one of them, so she bolts to a crosstown firm representing the opposition. From there, the film lays bare the dirty dealings carried out by lobbyists and special-interest groups, who will do anything to push their agendas through Congress. Sloane, with her flaming-red hair, scarlet lipstick spattered on like war paint, crisp power suits, and stiletto heels, confidently maneuvers through influential D.C. meetings, receptions, and dinners like a great white shark, devouring anyone who gets in her way."Were you ever normal?" someone asks Sloane, after learning about another of her dirty tricks. The incisive script, written by first-time scribe Jonathan Perera, hints at a troubled past, although it's never fully explored. The lack of backstory dehumanizes Sloane and makes her difficult to like, but, as played by Chastain in a sizzling, Oscar-worthy performance, she's never less than riveting. You simply can't take your eyes off of her as she delivers rat-a-tat, Sorkin-esque dialogue that allows her to display her withering intellect and cruel wit. She's a cross between Scandal's ruthless, over-prepared Olivia Pope and the titular merciless genius of Sorkin's Steve Jobs, neither of whom suffer fools gladly. You wouldn't want to work for her or be her friend (that is, if she had any friends), but you most certainly would want her in your corner in a dogfight.Miss Sloane boasts a terrific ensemble cast that includes Alison Pill as a Sloane clone who defies her idol; Gugu Mbatha-Raw as a whip-smart but meek associate who is forced into the limelight; Michael Stuhlbarg as a rival lobbyist determined to bring Sloane down; and Mark Strong as Sloane's new boss, who is shocked by his hire's duplicitous nature. Directed with crackling intensity by John Madden (Shakespeare in Love, The Debt), the movie occasionally gets bogged down in preachy political rhetoric, but thankfully, Chastain is always there to bring the scenes back to life with a scalding glance or witty retort. At a shade over two hours, Miss Sloane could have used a little trimming, yet viewers will quickly forgive the lengthy runtime once its powder-keg finale explodes and erupts in lively debate on the drive home.