Married couple Katherine & Mike are each on a mission to save the world. She's a scientist studying climate change; he's an astronaut exploring the unknown. When Mike's shuttle vanishes in outer space, Katherine forges ahead alone, raising their children and continuing her life’s work. ...Until Mike suddenly reappears on Earth years later without explanation. As the couple struggles to adapt to his strange return, they must try to reestablish their connection in the face of an uncertain future—for both their family and the planet they call home.