Based on Veronica Roth's best-selling novel (the first in a trilogy followed by "Insurgent" and "Allegiant"), "Divergent" does not entirely break free from its YA-literature origins, but is confidently helmed all the same. Convoluted though the premise is, director Neil Burger (2011's "Limitless") and screenwriters Evan Daugherty (2012's "Snow White and the Huntsman") and Vanessa Taylor (2012's "Hope Springs") believe in the story they are telling and spin it cohesively—sometimes at the expense of some wished-for thematic ambiguity. There is a lot to think about regardless of the film's tendency to explain itself rather than let the natural progression of the story pave the way, but the tenacity of the ensemble, led in no small part by the tremendously expressive Shailene Woodley (2013's "The Spectacular Now"), is what keeps one watching.

In a dystopian future society where Chicago stands in partial disrepair and the rest of the country was allegedly destroyed one hundred years ago by war, society is broken into five factions: the smart Erudites, the honest Candors, the peaceful Amity, the brave Dauntless, and the selfless, vanity-free Abnegation, who run the government. Each year, a new group of teens are given an aptitude test telling them which faction they are, and then are forced to choose for themselves. Beatrice 'Tris' Prior (Shailene Woodley), belonging in an Abnegation family with parents Natalie (Ashley Judd) and Andrew (Tony Goldwyn) and brother Caleb (Ansel Elgort), knows deep inside she doesn't belong in the faction she was born into, but is thrown for a loop when she learns she is the ultra-rare Divergent—that is, exhibiting characteristics from all five of the sects. Trusting her gut at the expense of losing her family, Tris chooses Dauntless and is tossed instantly into an extensive 10-week training period. Those that pass will forever be a part of the faction, warriors for the good of the nation. Those that do not make the cut will be stripped of all identity and rendered homeless. This pressure would be more than enough for any young person still struggling to find their way, but Tris faces even tougher stakes. In immediate danger if others find out she is Divergent, she nonetheless cannot just stand by and let her faction of origin be threatened when the Eruidites, led by Jeanine Matthews (Kate Winslet), prepare to overthrow Abnegation's humble rule.

At nearly two hours twenty minutes, "Divergent" goes a little long but hooks the viewer from the start. Presumably more setup for what is to follow in the next two books' adaptations, the film compellingly introduces its cast of characters and delves immediately into Tris' personal conflict and the fight about to be waged to bring order to her dictatorial society. Watching Tris' confidence and cunning develop as she aims to prove her capabilities to Dauntless leader Eric (Jai Courtney) and training instructor Four (Theo James) is palpably woven into the larger political allegory of a civilization struggling for freedom, peace and individuality under the thumb of fascism. A scene in which one trial calls for Tris to zip-line from a city skyscraper through burnt-out buildings and across the nighttime landscape is exhilarating, the equivalent of an amusement park thrill ride.

In her complicated, multi-tiered performance as Tris, Shailene Woodley exemplifies all the traits of a Divergent—a demanding necessity likely easier said than done. Unhappy about the laws of the current society but yearning to remain true to herself, Tris leaves her family but never stops loving them. The purveying guidance of "faction over blood" is one she does not—cannot—believe in, and Woodley is able to empathetically pull off a rainbow of emotional dissonance as she sees the people she cares about threatened and the regime before her asphyxiated with mounting totalitarianism. As instructor Four, Theo James (2012's "Underworld: Awakening") brings a tantalizing intensity and unanticipated warmth to a young man whose steely first impressions eventually give way to a drive to better himself and the injustices he sees occurring around him. Tris and Four's romance is an obvious requirement of the teen-targeted demographic, but they do elicit a burgeoning steam between them.

Bringing shade to some of the side roles, Zoë Kravitz (2013's "After Earth") is likable as Tris' closest friend during training, former Candor member Christina; Jai Courtney (2013's "A Good Day to Die Hard") is brawny and magnetic as Dauntless leader Eric; Miles Teller (2014's "That Awkward Moment") is underused but effective as hostile Dauntless trainee Peter; Ashley Judd (2013's "Olympus Has Fallen") brings an aching matter-of-factness to Tris' mom, Natalie, and Maggie Q (2011's "Priest") gives test administer/tattooist Tori a straight-talking but underlyingly compassionate demeanor. As predominate antagonistic face of the piece Jeanine Matthews, Kate Winslet (2011's "Contagion") is a plausible straight-faced bad guy, but this is a standard villain role, and not a satisfactorily developed one at that. Stuck acting most of her scenes out with folders covering her midsection (the actress was pregnant during filming), Winslet is too good for such a restrictive part.

Rising in strife and momentum as the story builds toward a temporary stopping point rather than a clear-cut ending, "Divergent" is a solid start to a new franchise for Summit Entertainment. Unlike Bella Swan in the "Twilight" pics, Tris does not need a man or a dreamy glittering vampire to define who she is and what her future holds. This by itself automatically renders Shailene Woodley's protagonist a more positive figure for young viewers, the troubles she faces instead resembling those that the noble Katniss experiences in "The Hunger Games." If "Divergent" occasionally too closely resembles that latter Suzanne Collins series, this is an unavoidable byproduct of being like-minded and vaguely derivative, both of them the result of demand within a young-adult market that knows what currently sells and has cultivated a formula to satisfy it. There is room for improvement in the finished edit, from characters who have abrupt turnabouts for the sole purpose of suiting the demands of the narrative to an overabundance of exposition when the film's themes are already loud and clear without these explanations. That the picture has deeper insinuations and more on its mind should be commended, however. A cogent testament to its overall success: when the movie ends, the urge lingers to find out what will happen next.