Jian Yan is a modern soul steeped in Cthulhu lore who transmigrates to a city in another world, perpetually shrouded in mist. The city seems peaceful, but in truth, Cthulhu's shadow has already seeped into it. Drawing on his unique forensic perspective, Jian Yan gets caught up in a series of bizarre cases. Fanatics determined to protect Cthulhu's secrets obstruct his investigations at every turn. As the investigations progress, the cases grow increasingly complex, and his sanity, or SAN score, keeps dwindling. Time is running out: if his SAN score hits zero, he'll descend into madness. Meanwhile, the local powers mistake him for a madman because of his knowledge of Cthulhu, and refuse to trust him. But thanks to his familiarity with the Cthulhu Mythos, Jian Yan manages to escape one crisis after another. Even if he ultimately uncovers the truth, however, his damaged sanity may keep him from ever returning to a normal life. Under mounting pressure, can Jian Yan pierce the mist and uncover the vast conspiracy behind the cases before his sanity is consumed, save the city, and keep himself intact...?
