Suicide Squad, book 4: Discipline and Punish
Ales Kot, Matt Kindt et Collectif2014

A NEW PSYCHOPATH IS IN CHARGE!

Back at their home base of Belle Reve prison after a disastrous mission, Amanda Waller realizes her task force of killers and misfits needs a new direction. After all, it's no coincidence that a team called the Suicide Squad would nearly self-destruct.

With everything upended, the Suicide Squad is now fighting for a cause they believe in, and working for a new commander - one of the most unstable serial killers the world has ever seen, with a mind as brilliant as it is twisted. Naturally, this mysterious, crazed killer in charge might be just what the Squad needs to get them working together as a team. And they'll need it for new missions against giant corpse-monsters, hypnotic anarchists and a face from Waller's past that she hoped she'd never see again...
(Collects Suicide Squad #20-23, the Harley Quinn tale in Detective Comics ~23.2 and Deadshot in Justice League of America #7.1)