Bing Liu is a 29-year-old Chinese-American film-maker, a former camera assistant on movies by Spike Lee and the Wachowskis whose first feature is a worthwhile documentary study of two guys from his hometown of Rockford, Illinois. They have effectively outgrown their former passion of skateboarding – it’s the director’s passion, too – and now face a difficult adulthood of responsibilities and unprocessed childhood pain. Bing has let his film evolve and grow naturally out of an extended process of interviewing the principals, comparing his own situation with theirs … and then seeing what happens. (Film-makers Erick Stoll and Chase Whiteside did something comparable with their excellent film América, which started as a study of a Mexican street entertainer and ended as a wonderful portrait of the man’s grandmother.)

There is much that is pertinent here about absent fathers and toxic masculinity, but Liu never quite settles on a coherent story and imposes on the film the slightly spurious unifying illusion that he and the two guys are friends who grew up together. In fact one is in his 20s, the other is a teenager and Bing only got to know them while making the film. (The video footage of them as kids has evidently been shot by family or friends.)

Zack Mulligan is an apparently amiable slacker, skater and drinker who has just become a dad but appears unhappy with the new situation of family responsibility and is now physically abusing his partner. Keire Johnson is a teenager coming to terms with being hit by his late dad. Liu has similar memories of abuse and Keire’s situation evidently inspired Bing to interview his own mother – a very painful experience. This is a fluent, watchable piece of work, though not quite as lucid as it might have been. A poignant tribute, at any rate, to the lost innocence of skateboarding.