Cthulhu's partner, Dagon, has been found floating dead in the water at the docks. The Elder Gods have given him three days to find Dagon's killer, or Cthulhu is going to take the fall for it. Starting on the trail of a femme fatale that had hired Dagon, Cthulhu begins searching for the Pnakotic manuscripts and finds himself on everyone's hitlist. Navigating a web of lies and betrayal, he becomes involved with a rogue's gallery of untrustworthy Old Ones who are after the coveted Silver Key. As things hurtle towards their inevitable conclusion, he discovers to what deadly lengths the others will go to obtain the Key.