It could be tempting to write off The Crusade as the equivalent of bumper sticker activism. After all, its 77 minute runtime doesn’t feel significantly weightier than chrome-bound catchphrases like “be the change you want to be in the world” or “think globally, act locally.” Louis Garrel’s coming-of-age fable is too clever to be discarded like that, though it might be as diffused as it is succinct in the end. There is still a generous charm in the film’s ambitions with wit every bit as sly as the teenage son at its center.

Joseph (Joseph Engel) has slipped possessions from his home, selling them to shadowy sources to support an ambitious plan to save the planet. This do-it-yourself GoFundMe is approached with certainty and immediacy, the naivety of the endeavor allowed to breathe sans condescension. That reaction is not initially shared by his comfortable and genial parents, Marianne (Laetitia Casta) and Abel (Garrel). The Crusade opens with their swift descent into disbelief as they unravel what Joseph has done, how he has taken objects and property from their benignly artistic flat. With hand-held camera work and real-time urgency roaming through the designed-by-Instagram home interiors, the early leg of the journey is stealthy and humorous.

A leather jacket here, a vintage Dior there–Joseph unloads the “useless” and “boring” collections of his parents, doing so unnoticed for months, down to his father’s cufflinks. His disclosure reaches a zenith when his mother and father recognize rare books (in Latin, which no one in the home can read) and wine are also missing, sold with proceeds delivered to a youth delegation concocting a massive initiative to fight climate change. The betrayal confounds Marianne and Abel. As open and liberal parents it exposes their hypocrisy and inaction. “Soon we will be like you, stuck and paralyzed,” Joseph explains in defense. There’s little in the way of argument in return because their son is right.

And here’s where The Crusade finds rays of perception. The realization that climate change is real and now, that ignoring the dying planet is further overlooking their child, sends Marianne and Abel into stages of discomfort and panic. Soon the crisis is no longer an abstraction of stolen wrist watches or shoes but all around after the government issues orders concerning toxic particles in the air. When Marianne dons a face mask to venture outside into empty Parisian streets, the symbolism is too exact but inarguably accurate, and as she contemplates a more proactive role in environmental activism her relationship with the more sceptical Abel is strained. When he excitedly, nervously, lugs home recycling sorting bags to meet her growing investment, the gesture is sincere but feeble. After all, their son has plotted with his peers to engineer the flooding of the Sahara Desert to save the world. Abel has purchased sacks.

Working from a screenplay he penned with the late Jean-Claude Carrière, Garrel contrasts the confusion of The Crusade’s adults with the resiliency of its youth. Joseph, whom his parents still call Jojo, is coming of age, but able to balance the environmental catastrophe at hand with his fledgling love life and awkward TikTok routines. The filmmaker avoids an outright embrace of the adolescent approach–the tale of the pious, semi-historical Children’s Crusade is, of course, disastrous–even as he suggests that confronting climate change is now an inextricable part of growing up. “They defend their world, not ours,” Marianne explains to her husband. As Joseph enlists his parents’ support, Garrel leaves enough room for cynicism, too, in a muddy but hopeful ending. Maybe Joseph has manipulated his parents in the same way a teenager might in extending a curfew or borrowing a car. Maybe it doesn’t matter when, as I saw on the back of a car once, there is no planet B.