Captain Burnham and her crew must go where few have gone before: beyond the Galactic Barrier. Meanwhile, Book learns the truth of what drives Ruon Tarka.

Saru returns to help the U.S.S. Discovery uncover the mystery of an unusually destructive new force. As Burnham leads the crew, she must also find a way to help Book cope with an unimaginable loss.

After months spent reconnecting the Federation with distant worlds, Captain Michael Burnham and the crew of the U.S.S. Discovery are sent to assist a damaged space station – a seemingly routine mission that reveals the existence of a terrifying new threat.