In the second-most anticipated Mark Hamill film released this year, “Brigsby Bear” is a tenderhearted comedy about the power of creativity and culture, even if it’s “just” pop culture. This is something I suspect Hamill might know a thing or two about.

Kyle Mooney of “Saturday Night Live” stars as James Pope, a young man who, like many young men, is very obsessed with a fictional character from his youth but who, like almost no other young men, grew up in an underground bunker raised by some very dedicated people who were also not his real parents.

The movie begins with an extended sequence from the television show “Brigsby Bear Adventures,” which has a big costumed bear character fighting a mustachioed evil Sun and awkwardly fitting in facts about math, hygiene and some more sinister sentiments, such as “Curiosity is an unnatural emotion.” James sits in his bedroom and watches, rapt. He looks like any other guy who is ironically obsessed with some analog artifacts from his youth; he has weird hair, glasses and a ringer T-shirt, but you can get all that stuff at Urban Outfitters.

James is called to dinner, where he shakes hands with people we assume are his parents. They seem well-meaning, but their eyes gleam with the intensity of zealots, and they all seem to share a passion for “Brigsby Bear.” When father and son head upstairs for “fresh air,” we realize they are living in an underground bunker, without any human contact — until, suddenly, human contact arrives in the form of the FBI to rescue James, who did not realize he needed to be rescued.

From this quirky situation, a sincerely sweet story emerges. James is plunged back into life with his real parents, who are overjoyed and overwhelmed to be reunited with their son after 25 years. Moving on isn’t so easy for James, who was brainwashed to be dependent and isolated, and he yearns for the next “Brigsby” adventure to be delivered.

Greg Kinnear co-stars as just one of a series of pleasantly supportive people James meets; his role in James’ life is one of the film’s many highlights.

James becomes determined to create a “Brigsby” film to finish the saga, an arguably unsubtle metaphor for his personal growth, but one that is so tenderly executed you can’t help but love it. With the help of his much younger sister and her friends, James embarks on a quest to bring the only story he has ever known to a satisfying conclusion, while his parents and therapist demand that he move on.

His real parents are a vital ingredient to this film’s success because, while the viewer cheers when people help James pursue his “Brigsby” obsession, his parents are also not wrong when they point out that “Brigsby” was a tool kidnappers used to control the son who was snatched from them as an infant. It’s pretty hard to argue with this logic, but I found myself yearning for James to reconnect with the felon who raised him — not the least because this person was played, of course, by Mark Hamill, a man whose psychological impact on so many people’s own childhoods falls just shy of kidnapping us and showing us only “Star Wars” until we were 25.

While the premise might sound impossibly quirky or fatuous, “Brigsby Bear” really pulls off a very moving and sweet film, a love letter to fandom and friendship and art that even honors a very troubled family dynamic in a touching way. It lacks Christmas music, but it is heart-warming enough for the holidays, and will pair nicely with the other Hamill-created universe to close out this year.

“Brigsby Bear” is currently available to rent.