Poseidon is a South Korean action-drama series that centers on the elite members of the Korea Coast Guard's Special Forces. The story follows the intense professional and personal lives of these officers as they combat maritime crimes, smuggling, and terrorism. The series highlights the high-stakes operations performed by the 'Poseidon' unit, a specialized team tasked with handling dangerous missions that regular coast guard units cannot manage. At the heart of the narrative is Kim Sun-woo, a talented but troubled officer who seeks redemption and justice after a tragic past event. As he joins the Poseidon team, he must navigate complex interpersonal dynamics, internal corruption, and the constant threat of criminal syndicates operating on the high seas. The show blends procedural police work with deep character-driven drama, exploring themes of loyalty, sacrifice, and the relentless pursuit of truth in the face of overwhelming odds.