Season 1 of Azure Abyss follows the successive appearances of gigantic aquatic creatures along Shanghai's Huangpu River. Master Chen, a street-food stall cook who sells late-night snacks, accidentally consumes a blue crystal found inside the remains of a giant crab. His body quietly evolves, and he develops a mysterious resonance with a giant eel. While the authorities impose a lockdown and investigate, they also rely on him to calm the colossal beasts. As a giant catfish attacks the city and an underwater offshore platform test spirals out of control, everyone discovers that the giant crab and eel were not the true invaders. Deep beneath the river lies a colossal blue gate that is beginning to awaken. The crisis temporarily subsides, but the real entrance has only just opened.