The story was basically a police detective uncovering ritual cult activity by immigrants (from some unspecified place) in a NY slum. And the narrator (the detective) goes on and on about these strange foreigners and their dark skin, weird languages, heathen religions, etc.

But it only occurred to me after finishing that, though the reader is told from the start that weird cult stuff will ensue, the detective doesn't actually find anything nefarious until pretty late in the story. So with the story's timeline it's mostly just a cop being suspicious of foreigners for being foreign, until many months later he suddenly discovers unspeakable horrors of etc. etc.