Batman and The Flash crossover in this four-part event spinning out of DC Universe: Rebirth! BATMAN #21 Art by: Jason Fabok Written by: Tom King The Dark Knight and The Fastest Man Alive, the two greatest detectives on any world, unite to explore the mystery behind a certain blood-stained smiley button embedded in the Batcave wall. What starts as a simple investigation turns deadly when the secrets of the button prove irresistible to an unwelcome third party—and it’s not who anyone suspects! It’s a mystery woven through time, and the ticking clock starts here! The story unfolds in Batman #21, The Flash #21, Batman #22 and The Flash #22 Discuss this story!