Not being a parent myself, all I know is what I have been told: that in the first days, months, maybe even years of having a child, you might be stunned by the idea that you are wholly responsible for the life of an entire person. "It's incredible," a friend once murmured to me, hours after delivering her son. "They're actually going to let me take him home. Like I know what I'm doing."

That's the thing about becoming a parent for the first time: All you can do is your very best, and what you believe is right.

In the upcoming film Captain Fantastic (in limited release July 8), a mother and father decide to raise their six-kid brood in the woods of the Pacific Northwest, eschewing convention in an effort to impart something more valuable than the comfort of the status quo — namely, meaning. Together, they school the kids in philosophy, literature, how to humanely hunt a deer in the forest, and so much more. It is an idyllic corner of the world that Ben and Leslie Cash have carved out for their children. But there is a crack in the foundation.

Leslie (Trin Miller) is ill. At the beginning of the film, Ben (Viggo Mortensen) is alone with the kids in the forest while his wife is in treatment for severe depression. She commits suicide little more than three months into her in-patient treatment. That is where the journey really begins: Leslie's wealthy parents ban Ben from her funeral, threatening to call the police if he interrupts the ceremony. He then has to decide what kind of parent — what kind of person and partner — he will be, without his wife's wisdom to inform his next move.

Understandably, the children are devastated by their mother's death, and by not being able to say goodbye. Leslie, a practicing Buddhist, has left behind explicit instructions for her remains: She wants to be cremated, her ashes flushed down the toilet in a highly public setting. (Trust me: When you watch the movie and get to understand the character, that last part will make perfect poetic sense. There is a wonderful wryness to this film that saves it from ever becoming too earnestly precious.) Perhaps not quite understanding what is at stake if they manage to fulfill their mother's wishes, the kids convince their dad to pilot the family bus — an actual school bus that has been outfitted like an RV — down to Arizona, so they can all say goodbye.