The crew of the U.S.S. Discovery joins forces with Captain Pike to unravel the mystery of seven mysterious red signals that have appeared across the universe.

A new signal brings the Discovery to a distant planet, Terralysium, that is inhabited by the descendants of human survivors of World War III, which was fought on Earth 200 years earlier.

The Discovery crew infiltrates Section 31's headquarters and suspicions arise that the crew may have a traitor in their midst. Meanwhile, Burnham tries to help Spock, but her efforts don't go as planned.

Burnham is stunned when she learns her ties to Section 31 run deeper than she ever fathomed. Armed with the identity of the Red Angel, the U.S.S. Discovery goes to work on its most critical mission to date.

Burnham receives the reunion she's been longing for, but it doesn't go quite as she imagined. Georgiou and Tyler sense a disturbing change in Leland.

A fourth signal leads the U.S.S. Discovery to an insular world, where Pike is forced to make a life-changing choice. Burnham and Spock investigate a Section 31 ship gone rogue, leading to a discovery with catastrophic consequences.

When the U.S.S. Discovery's crucial mission does not go according to plan, Burnham realizes what must ultimately be done. The crew prepares for the battle of a lifetime as Leland's Control ships get closer.