Book excerpt: As this latest collection of Flash tales written by Mark Waid begins, meet Walter West, a Flash from a parallel reality where his beloved Linda Park died and the speedster doles out brutal justice to criminals as a response. Can the two Flashes co-exist long enough to stop Replicant, a villain with the combined powers of the Rogues Gallery? Better find out fast-the longer Walter West stays on Wally’s Earth, the more he poses a threat to all of reality! Collects The Flash #151-162, The Flash Annual #12, and pages from The Flash Secret Files #2.