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.

Osyraa attacks Book's home planet and the Discovery travels there to help. Stamets and Adira investigate The Burn.

Seeking answers, the U.S.S. Discovery ventures into a subspace rift created by the Dark Matter Anomaly. Meanwhile, Book faces a strange visitor from his past.

While undercover in a pre-warp society, Captain Burnham is forced to consider breaking the Prime Directive when a local tradition threatens Tilly's life. Meanwhile, Culber tries to connect with Stamets, and Adira steps up when Rayner assigns them a position on the bridge.