Who are the Secret Six?: Part 1 of 5 

Up in the sky, in the dark of the night, trust no one-for the Secret Six walk among us. Spinning out of the devastating events of the Batman Who Laughs, Superman and Batman are together once more in an all-new monthly series-and they're facing a terrifying new threat that could strike from anywhere. The Dark Knight and the Man of Steel must journey into the depths of Gotham City to learn which of their fellow heroes has been transformed into the horrifying horseman of their most dangerous and deranged foe ever. Our heroes will need to fight to survive, but an even more dangerous question lurks in the shadows: Can Superman and Batman even trust each other?