Like its intrepid firefighter subjects, Tom Putnam and Brenna Sanchez’s Burn initially seems juiced up on too much adrenaline. Early in this kinetic documentary intimately following a tumultuous year in the life of Engine Co. 50, Detroit’s most aggressive and overworked fire brigade, every shot resonates with a breakneck immediacy and danger. But the endless scenes of burning buildings and macho posturing merely provide an action-driven context for the filmmakers to deal with more personal topics like loneliness and resiliency. That these themes apply to multiple generations of men working together makes Burn an even more intricate work of nonfiction. Firefighters may be “social creatures by nature,” as one interviewee puts it, but the film manages to peel away that façade and reveal the collective frustrations of a profession fighting for its life one individual at a time.