The story begins with Detective Malone describing an on-duty incident in Red Hook Brooklyn that gave him a phobia of large buildings. Back-tracking to where it all began, the Brooklyn waterfront slum Red Hook is described in detail, with its gangs and crime, and hinting at an occult underbelly. The "case of Robert Suydam" is then told to be the driving force behind Malone's federally ordered involvement at Red Hook. Suydam's demeanor changes suddenly. Known as a shabby recluse, he is seen around town looking younger and more radiant. News arrives of his engagement to a well-to-do woman, while, at the same time, there is an increase in local kidnappings. A police raid, involving Malone, uncovers nothing useful from Suydam's Red Hook flat save a few strange inscriptions. After Suydam's wedding, he and his bride leave on a ship. Aboard, a scream is heard and, when the crew enter Suydam's stateroom, they find him and his wife dead, with claw-marks on his wife's body. Later, some strange men from another ship come on board and lay claim to Suydam's body.

Malone enters Suydam's flat to see what he can find. In the basement, he comes across a door that breaks open and sucks him inside, revealing a hellish landscape. He witnesses human sacrifices and a ritual that reanimates Suydam's corpse. Malone is found in the basement of Suydam's flat, which has caved in inexplicably above him, killing everyone else inside. The tunnels and chambers uncovered in the raids are filled in and cemented, though, as Malone recounts, the threat in Red Hook subtly re-emerges.