HiC is about heroes trying to deal with fucked up shit, but the therapy is self help..
It kills off a few characters, some that were mostly background, or side characters in other books. Biggest ones were Poison Ivy, Arsenal, and Wally West (original).
Blame is put on Harley, and Booster as the ones who done it, both remember seeing the other do it. They play a game of cat and mouse to try to frame the other while the JL chase them down.
Turns out Wally killed everyone, lost control of the Speed force because depressed/insane over losing family and not trusting the therapy place, killed everyone around him in an accident. Got caught by Harley and Booster, knocks them out, and implants these false memories of each other killing everyone. Runs away a week into the Future to confess, and brings Poison Ivy back to life, through the power of the Green, and plans to kill himself.
It's not a bad read at all, more enjoyable without the spoilers, since it's a "who done it" story. I think it gets a lot more hate for character assassination of a fan favorite, and killing some characters people like. I think they just didn't know what to do with Wally, and black Wally is doing okay in Titans atm