Alternate History Western

Penumbra, a haphazard city of outcasts, rebels, and malcontents, has floated around a dead planet in a backwater system for longer than living memory can recall. Its towers abandoned starships melded to an ancient, mysterious core, Penumbra is the last remnant of chaotic individualism in a galaxy where conformity to the will of the all-powerful Galactic Council is paramount.

Movie star Mary Marvell consults with Hercule Poirot after receiving threatening letters that warn her to return her diamond, the famous ""Western Star,"" to its rightful owner. But who does own the diamond, and is it even the genuine article?...