The film begins with Sarah telling her Father that it is okay to let go. He's been infected with an unknown disease that has hit America. Later, the event that caps the story is Sarah having to say the same thing to her teenage son, Travis who becomes infected and dies as well. The film is about the death of a father and son, which relates to the personal story behind the film of Trey Edward Shults, whose own dad lost his battle with cancer and he had to say goodbye to him. We see the reality that death does not just strike the one whose life is lost, it effects forever those who must carry on after death.
The great mystery of where this outbreak came from belongs to the idea that death can come from anywhere. It is a mystery that cannot be easily explained. Will and Kim represent the idea of being carriers of death as they've escaped the epicenter of the outbreak in a major city. It is a choice that Paul and Sarah must make to choose to find the humanity for this family or reject them. This choice is debated as to what they are is represented in Will's screaming as he is tied up to a tree outside of Paul and Sarah's home. He has broken in to find water and supplies, and Paul knocks him out, ties him up and puts a gag in his mouth so, when he screams it's muffled. His muffled screams represent the potential that he is a human being who simply desires to live, there is humanity desperately crying for help; and the other belief is that there is something terrible inside of him trying to get out. By choosing to help Will, Paul and Sarah are choosing trust that there is humanity left, not only in the world, but in them.
In the end, the outbreak claims Travis and Andrew, but it is the fact that the families are willing to do anything necessary to protect their families that causes death. They become unwilling to negotiate with one another to the degree that Paul and Sarah shoot Kim, Andrew, and Will. It raises the question: when your own family is at risk, what will you do to protect them? In this case the answer is anything, and it costs them everything.
