The fight against Tarka ends and Species Ten-C halt the anomaly, as Discovery returns to the Federation.
Tarka begins dismantling the power source as plasma bursts erupt, and T'Rina learns that 10-C share a linked mind and do not realize Tarka acts alone. Discovery breaks out of the orb, Ndoye rams Book's ship with a shuttle to stop Tarka, who is killed, and Book appears to die.
The crew meets 10-C inside the hyperfield, and 10-C stop the anomaly before it reaches Earth and Ni'Var, revealing they have saved Book. Book's appeal from his own grief persuades them to end the anomaly and repair the harm. 10-C send Discovery home through a wormhole, Earth decides to rejoin the Federation, and Book is assigned to help others hurt by the anomaly. Michelle Paradise wrote the season finale.