Related Clues:

• Brain twister
• Puzzling person/thing
• Person still being portrayed as problem
• Tough query
• Hard problem
• It's a mystery why one might read Hemingway
• Mind-boggling puzzle
• Encryption machine featured in 'The Imitation Game'
• Show off funny prose
• Unoriginal person
• German cipher machine cracked by Alan Turing
• Source of wealth bearing good returns, a mystery
• It's hard to figure out
• "Sadeness (Part I)" electronic band
• Model for album cover