In a quiet village, a young boy named Duanmu Yeyu was once rescued by the elite "Hell Hunters" of Ember City. Greatly inspired by these heroes, he resolved to one day join their ranks. As Yeyu boards a bus bound for Ember City to pursue his dream, he is unknowingly drawn into a maelstrom of upheaval. The primary antagonist, Lucifer, dispatches a bioengineered operative named MIKO-Taiyi to infiltrate Ember City and steal classified data. During a fierce clash with the Hell Hunters, Taiyi is gravely wounded and loses consciousness. Yeyu discovers Taiyi and, unaware of Taiyi's true purpose, brings Taiyi back to the Hell Hunters' base for medical attention. In the process, Yeyu inadvertently takes a critical mission device from Taiyi. As Yeyu begins his long-awaited trial to become a Hell Hunter, his innocent action sets off a chain of events. Taiyi, desperate to evade detection by Ember City forces, must secretly approach Yeyu and retrieve the device. Meanwhile, Lucifer sends tens of thousands of minions to locate the missing Taiyi. Thus begins a citywide conflict triggered by a simple act of kindness, one that threatens to escalate into a battle for Ember City's very survival.
