(CNN)As much a documentary as a drama, "Patriots Day" is earnest to a fault -- a retelling, from multiple angles, of the Boston Marathon bombing, the lives affected by it and the desperate manhunt for the brothers who perpetrated it. The story can't help but be stirring, but director Peter Berg's spare, flag-waving ode to Beantown's beating heart frequently comes across as more dutiful than dramatic.
'Patriots Day' brings spare authenticity to Boston Marathon bombing
Basically, the movie is structured as a tick-tock of the events, recounted through the interlocking stories of a cop (Mark Wahlberg) drawn into the investigation; the Tsarnaev brothers (Themo Melikidze, Alex Wolff), who staged the attack; and various victims, from those caught in the twin blasts to the MIT university police officer shot by the Tsarnaevs to a Chinese exchange student (Jimmy O. Yang) who was carjacked by the pair.
Working from a script on which he shares credit with four others, Berg tautly captures the chaos and carnage, as well as the intense search to bring the duo to justice. That includes not just portrayals of the many real-life law-enforcement officials involved -- among them Kevin Bacon as the FBI agent in charge, and J.K. Simmons as a police sergeant from Watertown, where the suspects fled -- but extended glimpses of their real-life counterparts at the end.
HBO produced its own recent documentary devoted to the 2013 attack, and the individual stories are gripping. Technically, this reunion of director and star (Berg and Wahlberg teamed previously on the war story "Lone Survivor") conjures a strong sense of authenticity with its stark visuals and understated performances, and Wahlberg, a Boston native, has clearly taken the project to heart.
That said, Berg has so painstakingly sought to replicate those tense hours that the movie sacrifices something in the way of dramatic impact, making its march toward the end of the manhunt for the brothers -- which yields the movie's most harrowing sequence -- feel more procedural than suspenseful.
"Patriots Day" should nevertheless find a receptive audience in its unabashed patriotism, celebrating both Boston and America's can-do spirit. That includes an overtly stated message, delivered by Wahlberg's character, as to why such terrorists can never win in the long run.
The steely attitude displayed here helped birth the hashtag "Boston Strong" in the wake of the bombings. "Patriots Day" appears so determined to convey that uplifting resolve as to at times feel heavy handed, playing more like the inspirational tribute that it is than the fully realized movie it was intended to be.
"Patriots Day" opens in the U.S. on December 21. It's rated R.