"Golden Boy" star Theo James is hopping aboard the " Divergent " train as Dauntless faction member Four, according to studio Summit Entertainment . The 28-year-old actor, probably best known for his memorable (albeit short-lived) turn as Mr. Pamuk on " Downtown Abbey ," nabbed the lead role opposite " The Secret Life of the American Teenager " star Shailene Woodley , who will play heroine Beatrice "Tris" Prior. " Divergent " is based on the 2012 best-selling young-adult novel by Veronica Roth — a dystopian thriller in which society has been divided into five factions, each upholding a particular virtue. Upon their 16th birthday, citizens are tested to determine their place. When Tris' result comes back inconclusive (a.k.a Divergent), she leave her family's faction and joins up with the brave (or, some would say reckless) Dauntless faction. Tobias "Four" Eaton is one of the faction's instructors, an