When facing a new villain who emerges in Central City, called Turtle, Barry is sent back in time to the mid-20th century, where Jay Garrick is still a young Flash at the beginning of his career, who also deals with the threat of the same villain Barry faced in his time. Meanwhile, in the present, Wally tries to face Turtle alone, but is surprised when the veteran and now retired, Jay Garrick, decides to come out of retirement to help. Now four versions of the Flash face the same enemy in the past and present, having to stop Turtle from carrying out his plan to break the time barrier, while trying to understand the mystery behind this new villain.
