London, 1894. Inspector Henry Cutter is in an unconvivial temper. Then the murders begin. The first to die is Sir Aneurin Considine, a decorated but long-retired civil servant, is found dead amongst his beloved orchid collection, killed by a wound inflicted with surgical precision.

Soon, other victims suffer similar fates. More men in powerful positions; more murders that are gruesome but immaculately orchestrated. The perpetrator comes and goes like a ghost, leaving only carefully considered traces. Hot on the tails of this invisible adversary are Inspector Cutter, along with his hapless but endlessly enthusiastic sidekick, Sergeant Gideon Bliss.