Christina is on the verge of an incredible scientific breakthrough—one that will affect all of mankind. She's sacrificed everything for her work, including her relationship with the only man she's ever truly loved.

Booker's life is empty without Christina. She keeps saying it's over, but he can't help reaching out to her one more time—at exactly the wrong moment.

When Christina's experiment goes tragically wrong, it unleashes a destructive force with the potential to annihilate all life on Earth—and beyond. The only hope for the future of the galaxy is the fragile connection between two human hearts, and the power of unconditional love.