Barry and team Flash continues to train to increase his speed so that he can stop Zoom. The team is overworked, and Cisco suggested they take a break and go out to have fun and decompress, and Caitlin quickly agreed telling Barry that a break is what they needed. However, their fun was cut short when another speedster showed up at the club and robs everyone leaving them to believe they have been robbed by The Flash. The team later discover that the new speedster must be on Velocity-9, and the only person that came across the formula was Caitlin acquaintance a Mercury Labs employee name, Eliza Harmon. Eliza was able to developed Velocity-9 from samples Caitlin gave her to help with Jay's illness. Eliza alter ego Trajectory invades S.T.A.R. Labs, and imprisoned Barry, and demands more Velocity-, when they refuse she threatens Jesse's life, forcing Dr. Wells and Caitlin make more of the drug and implanted a GPS to track her. Trajectory took the formula and injects Jesse as a test then speeds off and creates havoc in the city. Barry tracks her down and tries to talk Eliza into giving up. She refuses and injects more V-9 into her system before speeding off. Barry watches as Eliza's speed becomes so intense that her lightning turns blue and she disintegrates. Meanwhile, Jesse decides to leave the city to experience the world on her own. Barry saw the similarity from Eliza overuse of V-9, and ties it to Zoom's speed and Jay's sickness. Cisco vibe’s and confirm Barry’s suspicion revealing to the team that Jay is Zoom.