The secret is that it steals super powers from those with super powers and gives those super powers to people without super powers. So a whole lot of infected people are probably going to be seriously disappointed when they realize they can merely speak with fish.
Last issue, the Amazo Virus was breached and Lex Luthor's warning computer said, "The infection begins now." Or something like that. That's a pretty dramatic warning to program into your security system. Instead of something like, "Risk of Infection now approaching 100%," or something more scientific, the computer simply acts like a stage production of "You're All About To Die" is just beginning.
This issue begins twenty-four hours after the Amazo Virus was set loose in Metropolis. Metropolis is mostly deserted except for a few sick looters. Biohazard Batman and Superman have been tasked with rounding up the infected and putting them in quarantine.
Symptoms of the Amazo Virus are random super powers. So it's like Bloodlines! Or the Terrigen Mist! Or any of the other various bombs, blasts, or airborne illnesses that have turned normal people into super heroes in the past.
Most of the rest of the Justice League have been infected and are dying. Batman seems to think finding Patient Zero is their best effort at curing the virus. Why? I don't know! Isn't that always the way? At least it gives Batman and Superman something to do. Lex Luthor (who, like Batman, was at the center of the exposure and is not infected) is taking care of the sick league members. Wonder Woman is hanging around with him casually threatening him to help her friends. She's immune to the virus because she's a demi-god.
Wait. If the virus wasn't airborne to begin with, did Patient Zero run up into the lab and snort it up his sinus cavity? Inject it into his veins? Dip his herpes-sores covered penis into it?
Turns out Neutron was trying to kill Lex Luthor for reasons that will be familiar to all comic book fans: somebody put out a generalized hit on Lex Luthor, payment going to the first super villain that succeeds. The next person in line is some guy named Bullet.
And then Superman and Batman find Patient Zero.
Jimmy? Jimmy Olsen?