WARNING: The following article contains spoilers for Batman/Superman #4 by Joshua Williamson, David Marquez, Alejandro Sanchez and John J. Hill, on sale now.

For a while now, we've known that while Bruce Wayne had defeated and locked up the Batman Who Laughs, the maniacal villain's nefarious plans would continue to haunt the DC Universe. Before the start of the new Batman/Superman series, the publisher had us wondering who were the Secret Six, the characters who had all been mysteriously infected by the Batman Who Laughs to become twisted versions of themselves. Little by little, the identity of these superheroes were revealed.

RELATED: Wonder Woman Is Humbled Before A More Powerful Wonder-Woman... From China

First came Shazam (as well as his alter ego Billy Batson), who attacked both title characters in Batman/Superman #1, Gotham City Police Commissioner Jim Gordon and later, Blue Beetle. Now, in Batman/Superman #4, Hawkman and Donna Troy join the Batman Who Laughs' team of twisted heroes, and the final piece of the puzzle arrives in the form of Supergirl. Finally, the Infected Six are revealed, and they have assembled.

But the question still remains, why did the Batman Who Laughs choose these heroes, specifically?

RELATED: A Divisive Bat-Armor Returns In Batman/Superman

In Batman/Superman #4, despite Bruce Wayne and Clark Kent's best efforts, the Batman Who Laughs' plan is coming to fruition. After infiltrating the Fortress of Solitude by disguising himself as Jim Gordon's bat-armor, the infected Blue Beetle attacks the two heroes. Soon after, Donna Troy and Hawkman both join the fight, and Batman and Superman quickly find themselves outnumbered. Fortunately, Supergirl shows up to lend a helping hand, but she doesn't remain an ally for long. Since Shazam was unable to infect Superman back in issue #1 of the series, the Batman Who Laughs has set his sights on another Kryptonian -- not Supergirl necessarily, but any of them he can get his hands on.

As Supergirl answers the call, she is quick to protect Superman from the Batman Who Laughs' infected Batarang. But in catching it to save her cousin, Kara Zor-El ends up infected in his place. Now, the Secret Six are all infected, and they have united in Superman's Fortress of Solitude.

RELATED: The DC Universe Faces A Threat Worse Than The Black Lanterns

But why did the evil Batman needs these six heroes, specifically? As it turns out, he needed Blue Beetle, Donna, Shazam, Hawkman, Gordon and a Kryptonian because each of them represents different energies the Batman Who Laughs needs to lock on the right frequencies that will allow him to open a portal to his dark universe. With the help of a Cosmic Tuning Fork built by Blue Beetle, the supervillain plans to bring his Justice League satellite, a gigantic weapon he will then use to infect everyone on Earth with the serum that made him what he is, over to his universe.

Therefore, the Secret Six may have been revealed, but they are only the start of the Batman Who Laughs' plan. With his sights set on the rest of the DC Universe and Batman and Superman outnumbered, the supervillain might actually win. It's what Batman does after all.

KEEP READING: General Zod Is Going to Hunt Down a Major Batman Villain