The CW says of “Versus Zoom”:
Equipped with the tachyon device, Barry believes he is fast enough to stop Zoom and wants to open the breaches to catch him. Harry strongly advises against that plan but after Barry convinces him, Harry reveals that Cisco has the power to re-open the breach. Meanwhile, Hunter Zolomon's painful story on Earth-2 is revealed.
Longtime talkbacker Shermdawg recaps last month’s “Flash Back”:
Last time on The Flash, Barry went back in time to consult Eobard Thawne's Harrison Wells on how to improve his speed force in order to cross back over to Earth-2 to defeat Jay Garrick who was recently revealed to be the villainous Zoom. Thawne reluctantly agreed when Allen threatened exposing his identity to Barry of the past before Thawne could complete his plans to return home.
While in the past, Barry tangled with past Barry, and sedated him in order to infiltrate S.T.A.R. Labs which was welcoming its latest prisoner....season one villain, Hartley Rathaway. Rathaway quickly sided with Team Flash when what Eobard called a "time wraith" slipped into their reality when Barry traveled to their point in time.
The wraith also made an appearance at CCPD where Barry ran into the now deceased Eddie Thawne. Remembering Iris had been thinking of him as it was coming up on the one year anniversary of his death, Barry asked him to record an on the fly (birthday message) telling her how much she meant to him, which Barry later shared with her when he returned home.
Before he made that return, Barry told Cisco that Hartley knew where Ronnie Raymond was, who at that time had been on the run as Firestorm. After sharing that knowledge and gaining Eobard's in the form of a flash drive to be inserted into the time vault's central console, he sped off into the particle accelerator's inner ring and lapped it building up enough speed to open a portal back to the future. Unfortunately the time wraith was hot on his trail despite Barry of the past helping him gain a little distance to successfully cross over.
When he did, he immediately asked Caitlin and Cisco if they had figured out how to kill the thing as it entered the lab. Cisco was confident that a sonic bullet would do the job but it had no effect as the wraith flew past him and put a death grip on Barry pinning him to the floor. Then...from out of nowhere...it was blasted off Allen and vaporized by the reformed Hartley Rathaway and his sonic gloves!
After saving Barry's life, Hartley bid his friends adieu before Team Flash (minus Wells who was too preoccupied looking for his runaway daughter) gathered in the time vault to view Eobard's formula for super speed and a way back to Earth-2.
