A fictionalized account covering the 2013 Boston Marathon bombing, from the evening before through the capture of the remaining suspect. Mark Wahlberg plays a policeman temporarily demoted to the street (reason for the demotion never covered). He swears a lot, works the finish line, and is heavily involved in the follow-up investigation. We see a number of what seem like random Bostonians going about their lives and jobs. This is of course heavy telegraphing: we're getting to know these people because they're going to be in danger or lose their lives.
With the exception of Mark Wahlberg constantly swearing, the movie is almost entirely lacking in humour - presumably out of "respect" for its subjects. This is one of the problems with making a movie like this so close to the events it portrays. The sense of place, the chaos at the finish line when the bombs went off, feels disorienting and horribly accurate. But as a whole, the movie is pedestrian: a respectful, patriotic, and somewhat boring retelling of an unpleasant event in American history.