Set against the backdrop of the Second Sino-Japanese War in 1941, 'Deep Lurk' follows the story of Yun Hongshen, a young man who returns to his hometown of Changsha to investigate the mysterious death of his father. Upon his arrival, he is thrust into a dangerous web of espionage and betrayal, discovering that his father was a secret agent for the Chinese resistance. As he navigates the treacherous political landscape, he must adopt his father's mantle to uncover a Japanese intelligence plot codenamed 'Kunlun.' As Hongshen delves deeper into the underground world of spies, he forms an uneasy alliance with Wen Yeming, a brilliant and determined operative. Together, they must outmaneuver ruthless Japanese intelligence officers and local collaborators while struggling to maintain their own identities. The series explores themes of sacrifice, patriotism, and the psychological toll of living a double life, culminating in a high-stakes race to prevent a catastrophic intelligence leak that could alter the course of the war.