mysteries

conundrum enigma problem question riddle secrecy subtlety thriller

abstruseness charade chiller cliffhanger crux cryptogram difficulty grabber inscrutability mystification occult oracle perplexity poser puzzlement rebus rune sphinx stickler stumper teaser twister whodunit why

brainteaser braintwister closed book inscrutableness mindboggler sixty-four-thousand-dollar question tough nut to crack

known understanding