Birth of the Dark Flash

The disappearance of the Flash had hit a nerve in the Arrowverse Justice League.
They need to pick themselves up and fight to face a threat far greater than a super villain.
They face... Themselves?
Overgirl peaks an interest in a Speed Force signature resembling one Barry Allen.
Demanding capture of the familiar speedster, she sends Dark Arrow to pay him a visit.
Barry is changed to lead again, to invade Earth 1, the home to the Scarlet Speedster.