Patriots Day, Peter Berg’s new drama about the Boston Marathon bombing, arrives in theaters less than four years after the attack, which left three people dead and hundreds more wounded. Sensitive to this, star­-coproducer Mark Wahlberg and director-cowriter Peter Berg take great pains to celebrate the humanity of those who were on Boylston Street near the finish line of the race in April 2013, when two pressure-cooker bombs exploded in quick succession, spraying shrapnel across the sidewalk. But Patriots Day functions mainly as a police procedural, chronicling the five-day manhunt for the two lone-wolf jihadists who manufactured the bombs, and in that regard it’s more valuable than any sort of exercise in healing. Within the confines of a hard-charging action flick, Berg and his coscreenwriters present a clear account of how media frenzy and fear of more attacks drove federal and local law enforcement to execute the first military-style lockdown of an American city.

The Tsarnaevs might have been apprehended more quietly than they were, but once the media forced the FBI’s hand, events began to spin out of control. Berg shows the brothers watching themselves on TV that Thursday and packing up their stuff so they can carry out more bombings in New York City. They roll up on the MIT campus, approach Officer Collier in his patrol car, try to wrestle his gun away from him, and pump six shots into him (he died on the scene). Immediately after this, they carjack a Mercedes SUV from a Chinese student and, heading through Watertown, get into a shoot-out with police. I’ve read accounts of this chaotic siege, but none of them re-create it as clearly as Berg does onscreen. Pulled over by a Watertown patrolman, Tamerlan opens fire, and as more squad cars roll up, the brothers begin hurling pipe bombs and detonating more pressure-cooker bombs. Pugliese arrives on the scene, but with no central command, the cops fire on the suspects from multiple directions; in the confusion, Dzhokhar runs over his brother with the Mercedes, and a Watertown officer almost dies from a bullet wound that was probably friendly fire.

Directed by Peter Berg