It was supposed to be one last job. At the behest of shadowy antiquarian Randall Tillinghast—who presents them with an offer they can’t refuse—our investigators travel to the South Pacific and the vast, alien city of R’lyeh. However, the more they explore, the more terrors they discover, and as a looming sense of dread grows, they find themselves—and all of Arkham—faced with a colossal threat.