About the title
The plot is built around three stories separated by centuries. In prehistoric times, a family of primitive humans loses their home and tries to survive. In the present day, anthropologist Claire studies human remains from the past while also dealing with her personal relationships. In the distant future, astronaut Coakley flies to a new planet while, aboard the ship, the plant life responsible for oxygen begins to die off. These stories don't directly continue one another, but they echo each other, showing how fear, hope, and human choice repeat across different eras.