A botched interview opens the new documentary Mistaken for Strangers. The subject of the interview is Matt Berninger, lead singer of indie-rock darlings The National. The interviewer is his ne’er-do-well younger brother (and director of the film) Tom Berninger, who clearly hasn’t prepared at all. As Tom struggles to come up with interesting questions on the spot, Matt’s already-worn patience gives out. “Do you have a notebook with questions written down?” Matt demands. “Do you have any kind of organization or plan for this film?” Tom doesn’t.

Recorded over the course of a year during The National’s High Violet tour, Mistaken for Strangers provides a fascinating look at the elusive band, but it’s the strained yet loving dynamic between the two Berninger brothers that gives the film its heart.

With his long, thinning hair, love of heavy metal, and slacker attitude, Tom Berninger is a poor fit for the prim, buttoned-up world of The National. He still lives with his parents, makes gory slasher films in his spare time, and has generally never gotten his act together. Hired as a roadie by his estranged brother as an excuse for the two to reconnect, Tom immediately begins to shirk his responsibilities in favor of shooting his documentary and partying. Tom’s attempts to interview the accommodating but increasingly uncomfortable members of The National make for amusing moments, as his lack of propriety results in questions that no respectable journalist would ever ask them. (“How famous do you think you are?” “How many drugs have you done?”)

The well-intentioned Matt soon finds himself pleading with Tom to just do his job, defending him to exasperated tour managers, or outright losing his temper at him, such as when Tom hilariously misplaces a guest list, leaving Werner Herzog and the cast of Lost waiting outside for 45 minutes. It’s endlessly entertaining to watch the fearless Tom stick his camera in the faces of unsuspecting celebrities like St. Vincent, Will Arnett, and John Krasinski. He’s genuinely shocked when the Secret Service won’t let him anywhere near President Obama, though.

The real surprise is that Mistaken for Strangers got made at all. Tom makes for a lovable fool at first, but as the film progresses it becomes clear that he’s crippled by self-doubt and a fear of failure. Once the tour ends, Mistaken for Strangers takes a meta turn as Tom attempts to find the movie in his endless hours of footage. He moves in with Matt and his unflappable sister-in-law Carin Besser, who provide creative and emotional support during the editing process. Since you’re watching the finished product, you know that Tom will eventually complete his film, but the lack of suspense doesn’t make Tom’s struggles any less affecting or relatable.

Mistaken for Strangers is a lot like its director: rough around the edges and a bit scatterbrained, but with an undeniable sweetness. It’s not the most technically accomplished documentary ever made, but the lack of polish gives the film a scruffy charm. Tom does get some stunning footage of The National’s amazing live performances though, and his insider access results in a much closer look at the band than fans have seen before. But the real reason to watch the film is for its emotional honesty. Mistaken for Strangers offers an unflinching portrait of the differences that can drive siblings apart, the creative crises that can derail the artistic process, and the way that unconditional love can lead the lost out from darkness.

Mistaken for Strangers is available in select theaters, On Demand, and on iTunes beginning Friday, March 28.