In a flashback, we see the moments before the Klingons attacked Burnham's home when she was a child.
She awakes in sickbay. Culber, Georgiou, and Pike confirm that the Red Angel is her mother. Spock brings the Red Angel suit's data and it is given to Burnham to analyze.
Leland awakes held captive by Control who intends to use his body to host its intelligence in order to continue its plan to gain sentience.
Burnham reviews her mother's mission logs and the bridge crew realize that the universe is trying to pull Dr. Burnham back through time, creating instability on the planet.
Control-Leland starts giving orders, attempting to gain possession of the Sphere's AI data by sowing doubt about Dr. Burnham's identity and giving Tyler the mission to steal the data from Discovery. Georgiou and Tyler are both suspicious.
Culber wakes Dr. Burnham and she asks to speak to Captain Pike and no one else. Burnham protests but she's left on the ship.
When Saru attempts to delete the Sphere data as Dr. Burnham recommends, it protects itself with a firewall.
When Burnham goes down to talk to her mother, it goes badly as Dr. Burnham is focussed on getting back to her time-travel mission.
The Discovery team figures out a way to send the Sphere data so far into the future that Control could never get it and possibly bring Dr. Burnham into their timestream at the same time.
Control-Leland sends Georgiou down to steal the data transfer and destroy the Red Angel suit and Dr. Burnham. During their conversation, Dr. Burnham explains that the AI sees her as "a threat to the larger mission", an exact phrase Control-Leland used in speaking to Georgiou earlier. She realizes that Control has Leland and contacts Tyler on the Section 31 ship to coordinate an interruption to the data transfer.
Tyler finds Control-Leland integrating the data and they fight which ends with Tyler being stabbed in the stomach. Leland beams down to the facility to restart the data siphoning. Georgiou fights him while Burnham and Stamets come to a decision to allow the time stream to take back the suit and Dr. Burnham. Once the wormhole takes them back, Discovery beams Burnham, Stamets, Nhan, and Georgiou back and destroys the facility. Control-Leland gets away but Tyler escapes in a pod from the Section 31 ship and gets picked up by Discovery.