Atomic part one!

The Atomic Skull is dead. When Batman and Superman arrive on the scene of his explosive demise, they discover that this villain-turned-would-be hero was one of many people to be the subject of grisly-and sometimes fatal-experiments. But who is pulling the strings of these bizarre and unnecessary surgeries? Whom will they experiment on next? And what does one of Superman's oldest foes, the Ultra-Humanite, have to do with this deadly mystery?