from the introduction:
“Night Floors” is a Delta Green scenario set in Manhattan, New York. The investigators play Delta Green agents and/or friendlies brought in to catalogue the articles of a missing painter. The bizarre tapestry of items in her apartment hints at something more than the everyday; for those few who can solve the mystery the rewards are reaped . . . elsewhere.
Some portions of the Night Floors scenario refer to material subsequently detailed in Dennis Detwiller's Insylum. You will want to review the relevant portions of the Insylum book if you are planning to use this scenario. Insylum is available from Dennis Detwiller's downloads page via his blog.