He tells them of a black magic book, the Necronomicon, believed to have been in Curwen's possession, and which Curwen used to summon the Elder Gods Cthulhu and Yog-Sothoth.
The man recounts a story about a black magic book called the Necronomicon, which was allegedly owned by Curwen and used to summon the Elder Gods Cthulhu and Yog-Sothoth.