"The Shadow over Innsmouth" is a horror novella written by H.P. Lovecraft, first published in 1931. The story follows a young man who visits the decaying seaside town of Innsmouth, Massachusetts, where he discovers its dark secrets and the strange inhabitants known as the Deep Ones. These creatures are part fish and part human, worshipping the ancient sea deity Dagon. As the protagonist investigates, he learns about the town's history, including its pact with the Deep Ones for prosperity in exchange for human sacrifices. The tale explores themes of isolation, forbidden knowledge, and the fear of the unknown, culminating in a chilling revelation about the protagonist's own heritage.