Barry travels back in time to get Dr. Harrison Wells to teach him how to run faster, but he doesn't realize the repercussion that comes with it.
After traveling to Earth-2, Barry Allen will next travel to the past. In the next episode of "The Flash", he returns to the time when season 1's villain Dr. Harrison Wells/Eobard Thawne is still alive to get Dr. Wells teach him how to run faster.
In a preview for the upcoming outing, Dr. Wells realizes that it's Barry from the future that he encounters. But the repercussion that comes with it is bigger than that as a mysterious black figure is seen attacking Barry.
Fans soon speculate that it's black speedster, but as some others note it, it's more likely the "time wraith" that comes as a consequence of Barry traveling to the past.
The sneak peek also offers a glimpse of Rick Cosnett's return as Eddie Thawne.
"Flash Back" airs Tuesday, March 29 at 8/7c on The CW. After the shocking revelation that Zoom is Jay Garrick, Barry is more determined than ever to get back to Earth-2 to stop Zoom forever. Desperate to find a way to increase his speed, Barry decides to travel back in time and masquerade as his earlier self in order to get his arch-nemesis, Dr. Harrison Wells/Eobard Thawne, to teach him how to run faster. However, things don't go as planned and Barry is stunned to face familiar foe Hartley Rathaway (guest star Andy Mientus), as well as old friend Eddie Thawne. Iris makes peace with her past in order to embrace her future.