Deadshot breaks into the Arkham Asylum to kill the Jojer, as he has been hired to do. In the midst of the job, however, another man shows up, who doesn't speak, except to repeat the noises he is hearing. He shoots Deadshot in the face, breaks the Joker out of jail, and hands him a suitcase filled with money to the Joker, who assumes that the man, who wears a black mask with two concentric cirles on the face, is there to have sex with him.
But when the Joker looks around, he's alone, and he takes the money and leaves. Meanwhile, Batman is defeating a criminal who has cut hashmarks all over his body. Well, except for one place. But as he contemplates cutting himself there, Batman breaks into the house and takes him down, then escorts the children to safety.
Right away, a cop tells Batman that the Commissioner wants to see him, and tells him "Code Green". Batman immediately goes to Arkham, where he finds the Joker gone, and Deadshot in an ambulance in a body bag. But Deadshot isn't dead, and Batman interrogates him, asking him why he broke the Joker out. But Deadshot didn't do it, and didn't want to do it- he was sent there to kill the Joker by the father of a victim of "Chuckles" a designer drug based on Joker's laughter poison. Batman learns that someone else freed Joker, the same person who shot Deadshot.
And the Joker is using the money he got to take on his former associate, Maxie Zeus. Maxie is a crime lord, the same one who is pushing "Chuckles", and Joker is quite peeved with him. He wants his poison to stay a poison, not a drug, and he threatens to take down Maxie with extreme prejudice if he doesn't stop pushing "Chuckles". And he destroys a school to push the point home. Zeus' nephew was in the school.
Joker also attacks Maxie's club, Olympus, taking over the position of DJ Mite and burning the club to the ground. Batman tries to intervene, but is attacked by both Joker and the new Villain. The villain shoots him, and disappears when the roof partially collapses, and Joker has already disappeared. Back at the Batcave, Bruce discovers that the bullets used by the new killer match to those used to kill two other vigilantes.
Batman goes to see Maxie Zeus, who is back to thinking himself a God. He had a psychotic break because of the death of his nephew Aesop. Batman breaks in and injects him with Anti-psych drugs and gets him to turn himself in to the Police. Joker goes there to look for him, and Batman, knowing he will, is there to take him in.
However, the Onomatopoeia killer is there as well, and there is a three-way fight on the roof. The O-killer shoots Batman in the head, and Batman survives due to armor. But can Batman catch the O-killer when to escape the killer is willing to knife Joker in the chest? Will Batman choose to apprehend the killer, or save the Joker's life? And how will his allies feel about his decision?
Well, this was certainly an unusual sort of killer for Batman to go after, and to be honest, it was very creepy to have him never say anything except to repeat sound effects. In the end, we never learn who Onomatopoeia is, except that he seems to have a normal life when he isn't running around killing people.
And in a way, that makes him even stranger than most of Batman's Rogues Gallery. Most of them don't have a normal life. Clayface isn't married, Joker doesn't have kids (and if he did, he'd probably end up killing them for yuks). Nor is Onomatopoeia from Gotham- he's just a visitor to town.
But aside from what we do know about him, what we *don't* know makes him even scarier. Why is he killing vigilantes and costumed heroes? Is he doing it for money, for his own kicks, or for some other reason? We don't know and are never told, and the mystery makes him all the more chilling. He's a real unknown factor, and we don't know what he will do, or what he could do.
So far, he seems to be just as ruthless, and maybe even more so, than Joker, and that's saying something. He's certainly as careless of lives as the Joker is, and shows no remorse for killing anyone. But the mystery of who he is- is not solved here. And I can't say that I didn't enjoy the story. In fact, I found it very effective. Recommended.