was just fishing, how did I become a Great Old One?

Jiang Li, a young woman driven by a desire to provide for her mother's medical expenses and her younger sister's tuition fees, takes on various part-time jobs to make ends meet. When she hears about the lucrative fishing opportunities in Blackwater Bay, a mysterious location outside the city, she sets out to catch the prized fish, armed with a cheap fiberglass rod from an online retailer. However, the waters of Blackwater Bay are treacherous, home to a bizarre array of sea creatures, including a fish with a human face, an octopus reciting sutras underwater, and a massive, elusive shadow that only dares to surface on stormy nights. As Jiang Li attempts to reel in these "big fish" with her unyielding fishing line, she finds herself entangled in a world of supernatural wonder and adventure.