Related Clues:

• Whodunit's essence
• Mark on a map
• Secret scheme
• Columbo question
• Bit of land
• Basis of a novel
• Cause for a crime
• Makings of a coup
• Stove feature
• Conspirator's creation
• Schemer's creation
• Be a schemer
• It might have a twist
• Book basis
• It might consist of a 19-Across