The young Ultimates are put to the test as they try to survive their first mission: going head to head with the city's most ruthless gang, the Serpent Skulls, led by Diamondback! Meanwhile, detective Brigid O'Reilly and her anti-gang unit are on the hunt for a serial mask killer called Scourge! These young heroes have fought Galactus, but can they survive super-powered psychopaths?