CANNES -- What if you were to learn that you are not the man you think you are?

And even worse, what if your family learned it at the same time you did?

That is the question that is cannily posed by "Force Majeure," a new film written and directed by Ruben Ostlund, and with one minor quibble, I found myself deeply impressed by how complex and smart the movie is, and how well it sets up that question and then spends time digging deep to try and answer it. Ostlund pulls off a remarkable balancing act of tone throughout the film, and while many movies feel like they work overtime to try and reach some sort of profound statement, "Force Majeure" effortlessly offers up an examination of just how difficult it is to define and live up to modern ideas of masculinity.

Tomas (Johannes Kuhnke) and Ebba (Lisa Loven Kongsli) plan a family vacation to Les Arcs, a beautiful ski resort in the French Alps. Ebba makes it clear that she considers this five-day trip to be important, since Tomas spends so much of his time consumed by work. She wants him to focus on his family, and Tomas seems totally up for it. And why not? Les Arcs looks like an incredible place to spend a vacation, and Tomas seems truly fond of his children, Vera (Clara Wettergren) and Harry (Vincent Wettergren). Everything is set for what should be an amazing, memorable trip.

Things change forever, though, when they are having lunch at the beautiful restaurant at the top of the resort, with an view of the surrounding slopes. There's a cannon blast, setting off one of the controlled avalanches they use to keep the slopes safe, and as they start to watch the snow roll towards them, it becomes clear that the avalanche is nowhere near as controlled as they would like. It takes a moment for the danger to set in, though, and when it does, it seems to be too late. Ebba leaps up to throw herself onto her children to keep them safe, while Tomas also jumps up… but without looking back, he runs for safety, taking only his iPhone with him.

Within moments, as things settle, everyone on the patio realizes that it was just a cloud of white fog kicked up the avalanche, and that they are indeed safe. Even their plates are intact, and people file back out, ready to continue lunch. When Tomas joins his family, he tries to shrug off what just happened, but for Ebba, there's no going back.

The film uses the daily structure of life on vacation to show us small variations in how things work between Tomas and Ebba, and once the fractures start to appear in their marriage, things get bad very quickly. At first Tomas tries to deny her interpretation of events, but once he's confronted with actual cell phone video footage, he can't lie to himself or to her anymore, and he has to deal with the idea that when a moment came for him to protect his family, he failed completely. I have said many times that I would step into the path of a speeding bus for my children, and I believe in my heart that I would, but until we are truly tested, we don't know. Historically speaking, it is the place of the man in a family unit to provide and to protect, but in modern Western culture, what are we really protecting them from? We do not face daily life-threatening challenges. We live a soft life, and if we're honest about things, we have to admit that we have become something other than what we once were. When Tomas runs for his life, he doesn't make the conscious choice to flee. It is a reaction, nothing more, and it haunts him.

When Matts, an old friend to Tomas, shows up with his young girlfriend to join them, Ebba finally lays all of her cards on the table, and the disappointment and the hurt she feels come bubbling over, leaving Tomas emotionally raw. One of the greatest tricks that Ostlund pulls off as a filmmaker here is how he manages to find very real humor in the midst of the pain and the doubt that these people face, and he does so without undermining the film's more serious points. It's an impressive feat, and Ostlund is just as strong a visual artist as he is on the script level. The film was photographed by Fredrik Wenzel and Fred Arne Wergeland using an ARRI Alexa, and it only makes yesterday's viewing of "Maps To The Stars" more painful. It is possible to create rich, textured, gorgeous digital photography, and Ostlund has used invisible visual effects to augment the real ski resort where they shot the film, creating a place that I would love to visit if it were real.

Kuhnke and Kongsli are both tremendous in the film. He has to chart the slow crumbling of ego as Tomas realizes who he really is, and Kongsli's reaction to his actions and his refusal to accept responsibility at first is expertly charted. She doesn't just switch off like a light switch. Instead, she is just as torn about her own feelings as he is. There is a lovely sense of married affection between them at the start of the film, and seeing that fractured, perhaps beyond repair, hurts because this is not a bad marriage. It's simply a union that has reached a pressure point, a state of crisis, and neither of them is sure how to survive it.

My only real complaint is that I feel like the last fifteen minutes or so of the film can't quite land the punch that it's obvious Ostlund is throwing. I get what he does and how it wraps things up, but the film is so good before that point that a fumbled ending sticks out as particularly hard to swallow. Even so, "Force Majeure" is an impressive and adult piece of work, bracing and intelligent. I had a hard time shaking the questions it raised, and even now, a full day later, I have no idea how I would face a similar situation.

Good films entertain us as we watch them. Great films linger. And this one seems like it's going to stick with me for a while.