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—the 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, the investigators find themselves—and all of Arkham—faced with a colossal threat.

The time has come. Cthulhu has awakened, and Arkham will never be the same.

In The Drowned City Campaign Expansion, one to four investigators explore the mysterious and deadly city of R’lyeh as it rises from the ocean’s depths. As players venture into the tomb-like ruin, they’ll scale the city’s crumbling foundations, scour the sea floor for alien artifacts, navigate mind-bending machinery and shifting corridors, and discover an ancient history that was drowned with the city itself. Along the way, they’ll experience a unique story that changes based on their chosen investigators, and it all culminates in a climactic battle against Cthulhu himself!