Related Clues:

• Mysteries
• Spies' quest
• What tellers lack?
• Spy's quest
• Spies seek them
• Classified stuff
• The unexplained
• Classified items
• Kept things
• Confidential things
• Bad things to share
• "... edged tools [to] be kept from children and from fools": Dryden
• Exchange of spies, maybe
• Things to keep
• Concealed stuff