Related Clues:

• Do the fly-by-nights return to get their knife into you?
• They might come back by night with a dagger (4)
• Take a knife to the fly-by-nights back there
• How a knife might make one turn mad
• Stick in the back and mad from the back
• Wound them if they fly by night
• Get your knife into the fly-by-nights back there
• Gets wound to fly by 22 across back here
• Get your knife into the fly-by-nights up there
• It's an attempt at?
• The knife wound turns one mad
• Attack a la Norman Bates
• Harpoon, e.g
• Semi-educated guess
• Use a shiv