The plot concerns a descendant of Joe Sargeant, a minor character from Lovecraft's short story The Shadow Over Innsmouth, who travels back to Innsmouth on the promise of a governmental promise of a payout over historical claims of property destruction.
As the story progresses Bob Smith, the descendant, discovers that the payout story is merely a lure by the government to trap and study Deep One Hybrids like himself when he is incarcerated in a prison-like facility in his ancestral home.
Later, Smith is revealed to be a serial killer who practices Deep One rituals on his victims and, after escaping the facility, transcends to the next stage in hybrid evolution before taking to the sea with his new-found Innsmouth bride.
Behind the Mythos
The Doom That Came to Innsmouth was first printed in Tales Out of Innsmouth, then in a revised format in Even More Nasty Stories by Wildside Press. It received an ebook release in another of Wildside's publications, The Cthulhu Mythos Megapack.