artful vs cloak-anddagger

artful

adj
  • Not naturally produced; artificial; imitative. 

  • Characterized by, or performed with, cleverness or contrivance; clever, ingenious. 

  • Skilful at using dishonest or unfair means to achieve a purpose; crafty, cunning. 

  • Exhibiting or using much art or skill; dexterous; skilful. 

cloak-anddagger

How often have the words artful and cloak-anddagger occurred in a corpus of books? (source: Google Ngram Viewer )