Season synopsis
Contains spoilers for this season and earlier seasons.
Nora West-Allen arrives from 2049 and tells Barry and Iris that she is their daughter. She wants to know her parents and help the Flash, while secretly consulting the imprisoned Eobard Thawne, the Reverse-Flash. The season’s other threat is Cicada, a dagger-wielding meta who can dampen nearby powers and has been killing metas across Central City. Sherloque Wells investigates Nora’s timeline, while Barry and Iris disagree over how much to trust their daughter and how far to go to protect her.
Team Flash identifies Cicada as Orlin Dwyer, who was impaled by debris from DeVoe’s satellite on the night his young niece Grace fell into a coma. Grief turned him against all metas, and the team eventually persuades him to take the metahuman cure. As he recovers, a second Cicada appears: the adult Grace from the future, who has inherited her uncle’s mission. Nora learns that Thawne has steered her actions toward destroying the dagger that keeps him powerless in 2049, using her attachment to her parents and her wish to stop Cicada to shape events.
Ralph connects the timeline’s contradictions to Thawne’s manipulation, but the final fight still forces Barry and Nora to choose between stopping Cicada II and preserving the dagger. Nora enters young Grace’s mind and convinces her to wake and accept the cure; the dagger fragment in Grace’s head prevents it from working until Barry destroys the dagger. Adult Grace disappears, and Thawne is freed in the future. Barry and Nora confront him, but the timeline changes around them. Nora’s speed begins to fail, and she refuses Thawne’s offer to save herself by entering the Negative Speed Force; she is erased from the revised timeline while Barry and Iris hold her.