For a director who built a remarkable career around filming his own life — for better or worse, through thick and thin, commenting on it with plenty of wit and wisdom — putting together a movie like Remake still had to be the hardest thing imaginable.

And yet 78-year-old Ross McElwee’s latest documentary, which explores the death of his son Adrian from a drug overdose in 2016, continues in the vein of the filmmaker’s best work, albeit with more emotional weight than ever before.

Ostensibly, Remake is about two things. On the one hand there’s Adrian’s long battles with drug addiction and mental health, seen from his own point-of-view and that of his father, who’d been filming Adrian since he was a child. And on the other there’s a very different, much lighter story involving a Hollywood director (Steve Carr, whose credits include Daddy Day Care and Paul Blart: Mall Cop) trying to turn McElwee’s classic 1985 doc, Sherman’s March, into a feature-length comedy. Or a series. Or a sitcom for streaming.

Like most of McElwee’s films, including Sherman’s March itself, this one juxtaposes two seemingly unrelated things in surprising and thought-provoking ways. A deeply troubled son and a movie remake would seem, on the surface, to have nothing in common. But the two are both ultimately about legacy — about what you create and leave behind. There’s also the fact that Ross McElwee is only vaguely interested in his most famous film being turned into fiction, whereas Adrian McElwee, who’s more commercially minded, think it’s a solid big-money idea that his father is compromising by insisting on artistic integrity.

There are many more layers here, which the film gradually peels away to reveal the tragedy at its core. As we watch Adrian grow up, from a curious and precocious kid to an adult beset by addiction, his dad seems to question everything we’ve seen both in his home movies and the ones released in theaters, which are part and parcel of the same oeuvre. “I used to call myself a filmmaker, I used to call myself your father,” McElwee laments repeatedly in voiceover after Adrian has passed away. It’s then that we realize how Remake is also about the impossibility of getting to remake your own life.

That life, at least as McElwee reveals it here, is filled with many highs and lows both personal and professional. We see him dealing with Adrian’s relapses, but also taking his son around the world, inculding on trips to Venice for premieres and parties. We seem him get married and then divorced decades later, then walk into a screening of his own wedding ceremony at a film festival in the Czech Republic. He wants to stop the show and tell everyone that what they’re watching is fiction, not documentary, which loops back to the whole idea of Remake in the first place: If reality isn’t actually real, then maybe everything should be fiction — so why not just accept a cheesy fictional remake? Or maybe reality is so horrible that it’s better to fictionalize life than to document it.

McElwee’s movie is bursting with such questions and ideas, though they don’t take away from its raw emotional power, especially as we get closer to Adrian’s death. At that point, the director focuses on the months leading up to the day his son tragically overdosed on fentanyl in the family bathroom in Cambridge. A little before that, McElwee inserts an extremely candid interview in which Adrian, who has just gotten out of another rehab program in Colorado, discusses his addiction problems with honesty and intelligence.

Some of those later scenes are tough to watch, but McElwee has made it his life’s quest to record everything he experiences, then to edit with the remove of an artist. He keeps finding links between himself and his son — not only the fact they look alike but that they both had a passion for filming, whether it was Ross with a 16mm camera or Adrian with iPhones or GoPros. At one point, we see clips of a documentary that Adrian was working on before he died. He speaks with friends and fellow addicts about their lives, getting them to reveal themselves just like some of the characters in his father’s films.

Among the latter, McElwee pays a visit to his longtime friend Charleen Swansea, who stole the show in Sherman’s March with her boisterous real-talk and raunchy humor. (Swansea was also the star of McElwee’s 1977 doc, Charleen.) But now, the woman suffers from Alzheimer’s and is unable to recall that they once made a movie together. “Things just disappear,” she tells the director as he continues to shoot her. He then cuts in footage from the good old days, as if to certify, both for himself and for the viewer, that these things really happened and were captured on film for posterity.

Time and memory have always been a part of McElwee’s work, which delves into his past and that of his family (Adrian featured prominently in his 2011 doc, Photographic Memory), as well as the past of America itself. Remake is certainly a movie about memory, especially bad memories, but in a Proustian sense it’s a movie in search of lost time — both the time McElwee spent with his son and the time slipping away as the director and his peers grow old and die. It’s also about the time wasted on a Hollywood remake that, of course, never sees the light of day. The most courageous thing McElwee does in this latest, heartbreaking work is to keep on filming even during the worst of times, not to make them stop but to make us remember.