The Night of the 3rd Ult.

The Night of the 3D Ult. [copyright 1890]. First edition, first issue.

Set in London, in a lower class boarding house, and concerns the doings of both a police detective and a private detective. Bleiler calls the ending of this novel “almost brilliant.” OCLC locates only three copies of this title, including the deposit copy at the Library of Congress. A significant and very scarce detective novel.

Image and description via Books and Art

This sounds like just my type of book. Too bad it is so rare.