As children, Kathy, Ruth, and Tommy spend their childhood at an idyllic and secluded English boarding school. As they grow into adults, they must come to terms with the complexity and strength of their love for one another while also preparing for the haunting reality awaiting them.

Fifty years into the future, the sun is dying, and Earth is threatened by arctic temperatures. A team of astronauts is sent to revive the Sun — but the mission fails. Seven years later, a new team is sent to finish the mission as mankind’s last hope.