Clue #1: 46 black ones.
Clue #2: "You known religion has a lot to answer for"
Clue 3#: "Ce soir, ce soir, assassination"
Clue 4#: "Four times fifty living men, (and I heard nor sigh nor groan)/With heavy thump, a lifeless lump, they dropped down one by one."
Incorrect guesses: The Edge of Darkness, Dance of Death, Fear Is the Key, Empire of the Clouds, Revelations, For the Greater Good of God, Kill Me Ce Soir, Be Quick or Be Dead, Age of Innocence, Holy Smoke