WARNING: The following contains spoilers for Dark Nights: Death Metal - Speed Metal #1 by Joshua Williamson, Eddy Barrows, Eber Ferreira, Adriano Lucas and Steve Wands, on sale now.
Speed Metal #1 takes place right after the events of Dark Nights: Death Metal #3. After Wonder Woman and Batman lead a rescue mission, they free Superman and the rest of the Justice League heroes. They then devise a plan to fight back against the Batman Who Laughs and Perpetua, the Mother of the Multiverse.
With the Batman Who Laughs now transformed into the Darkest Knight, all that's left for him to do to become to most powerful being in the Multiverse is to get his hands on Wally West and take his Anti-Crisis Energy.
The all-powerful villain starts racing after Wally, who is joined by both Barry Allen and Jay Garrick. Together, all three characters run into the Speed Force in Speed Metal #1 to try and get away from the Batman Who Laughs. However, he hasn't come alone. The Darkest Knight unleashes his scariest army yet on the Flash Family: A legion of Dark Flashes.
At the start of Speed Metal #1, the Batman Who Laughs -- in the guise of a massive, nightmarish cloud -- follows Jay, Wally and Barry into the Speed Force. Soon, the trio of speedsters are joined by Wallace West. Kid Flash starts running alongside them as they bring him up to speed on what is happening and what is at stake. However, they are then interrupted by the frightening sound of war drums. The drums warn of the coming of a horde of Dark Flashes from across the Dark Multiverse.
In Dark Nights: Metal and it' sequel Death Metal, it was revealed that the Dark Multiverse is the home of twisted realities born of the fears of main DC Universe characters. There have been dozens of alternate versions of Batman who hail from this realm, such as the Grim Knight, Darkfather, the Robin King and many, many more. Worse still, they have all acted as the Batman Who Laughs' enforcers. As revealed in Speed Metal #1, the Darkest Knight has also assembled dozens of Black Flashes.
In the DC Universe, the Black Flash essentially plays the role of Death for all characters who have superspeed abilities. The Black Flash is a wraith who runs through the Speed Force, claiming the life of a speedster when their time is up. Generally, this Flash has the appearance of the Scarlet Speedster, only with a black suit instead of the usual red.
Most of the Batman Who Laughs' army of Dark Flashes is comprised of these zombie-like Black Flashes, but there are a few notable debuts -- such as a Gorilla Grodd Dark Flash, a Batman-inspired Dark Flash and perhaps most troubling of all, a Joker Black Flash.
Together, they form a frightening horde of ravenous zombie speedsters and they prove to be a challenge for Barry, Jay, Wallace and Wally. In fact, they are able to pick them off one by one: Jay remains behind to deal with the horde and he is eventually joined by Wallace, who can't keep up with Barry and Wally.
The Dark Flashes even manage to catch up to Wally, but he is finally able to reach his destination -- the Mobius Chair -- before they can stop him. The Flash Family may have won this race, but the Batman Who Laughs could still bring this army back to continue to go after the speedsters.