Twenty winters have passed since the Cataclysm brought down society and robbed people of their memories. Humanity, vastly reduced in numbers since the initial chaos, has started anew in Canal City with the aid of library books and steam technology. The Scout and Ranger Corps was established to search for possible survivors and to replenish dwindling resources.

Dev is the captain of the scout airship Smoke Sparrow, and Shay is the scholar of their newest expedition. Their destination is Innsmouth, Massachusetts, a small fishing town that is mentioned in obscure books but shows up on no maps. Might its secrets offer answers? But within the fog-covered, ruined hillside town by the bay lurk unspeakable dangers and horrors beyond imagining. The expedition team soon learns that Innsmouth is one town that should have been left forgotten.