In August, an artist is found murdered in his home - stabbed with a pair of scissors. Matthew Harvey's death is much discussed in the city. The scissors are among the tools of his trade - for Harvey is a renowned cutter and painter of shades, or silhouettes, the latest fashion in portraiture. It soon becomes clear that the murderer must be one of the artist's last sitters, and the people depicted in the final six shades made by him become the key suspects. But who are they? And where are they to be found?
Later, in November, a clever but impoverished young gentleman called Fletcher Rigge languishes in the debtor's prison, until a letter arrives containing a bizarre proposition from the son of the murdered man. Rigge is to be released for one month, but in that time, he must find the killer. If he fails, he will be incarcerated again, possibly for life.
And so, with everything at stake, and equipped only with copies of the distinctive silhouettes, Fletcher Rigge begins his search across the snow-covered city, and enters a world of shadows...