The Stony Island adventure is a good introduction to the weird world of the Black Cat Detective Agency.  Use this as a first assignment for the player characters.

Stony Island is a very small island off of Belle Isle in the Detroit River.  It is considered quite down-river, just north of Bois Blanc (formerly the Boblo Island island amusement park). On April 23rd the residents of Stony Island disappeared with no obvious explanation.