Season synopsis
Contains spoilers for this season and earlier seasons.
A girl named Dawn suddenly appears as Buffy’s younger sister, and the family and their friends remember her as if she had always been there. Buffy remains wary until she learns Dawn is the Key, a mystical energy that can open a portal between dimensions. The hell-goddess Glory is searching for it so she can return to her own dimension and unleash chaos; she shares a body with medical intern Ben, and the two increasingly affect one another. Buffy’s focus shifts from college to protecting Dawn and caring for their mother Joyce, whose headaches prove to be caused by a brain tumour. Riley leaves Sunnydale, while Spike accepts that he loves Buffy and begins helping the group. Joyce later dies from an aneurysm, leaving Buffy and Dawn to grieve.
Glory discovers Dawn's identity and kidnaps her for a ritual at a tower. Willow attacks Glory and restores Tara's sanity, while Buffy fights using Olaf's hammer. When Glory reverts to Ben, Buffy spares him, but Giles kills him to prevent the goddess returning. Up on the tower, the demon Doc defeats Spike and cuts Dawn, starting the ritual with her blood. Buffy reaches Dawn and pushes Doc away, but the portal opens. Dawn is prepared to die to close it; Buffy realises her own blood can serve the same purpose and jumps instead. Her death seals the portal, preventing the dimensions from collapsing into one another. Her grieving friends bury her beneath a headstone that credits her with saving the world.