Arkham Light with Cthulhu Dark
Setting: Arkham, Massachusetts in April 1924 (times are good)
Languages: English (Italian and Polish are in use by immigrants but not necessary)
Style: Noir film purist with pulp streaks.
Laws are enforced, use of firearms is legally risky but it happens. Any race and gender of PC can be explained in context of counter-culture criminals though New England stock and Irish Catholic immigrant backgrounds are the most plausible.
General public and authorities are unaware of the mythos, no PC’s started aware of it.
Investigators are the Friends of Mickey Finn, brought together by the events surrounding Judge Birch’s death.