: The story offers tantalizing glimpses into Bart's origin in the 31st century.

In the 2013 New 52 continuity, The Flash #21 gave fans a long-awaited "race of the century" between Barry Allen and the impulsive teenager Bart Allen, also known as Kid Flash.

: Barry Allen and Bruce Wayne team up to investigate a blood-stained smiley face button found in the Batcave.

: Believing Kid Flash might be linked to a series of Speed Force murders, Barry chases the bratty teen across the globe.

: The issue focuses on the tension between Barry Allen, who believes speedsters shouldn't be soldiers, and a version of Wally that has been pushed to the edge. ⚡ Key Takeaways for Collectors The Flash #21 review - Too Dangerous For a Girl 2

In the world of DC Comics, "The Flash #21" has been the title of several major turning points across different eras. Whether you’re looking at the iconic "The Button" crossover or the first meeting between two generations of speedsters, these issues are legendary for redefining what it means to be the Fastest Man Alive. The Button: A Collision of Worlds