Logic Puzzles - Solve Online or Print Your Own for Free! Knights and Knaves - newheiser. For starters, neither B nor C can be the knight.
C can't because he claims to be the spy, and B can't because he claims someone else is the knight. Therefore A is the knight. B is saying something true, so he must be the spy, making C the knave. In this case, B obviously can't be the spy because then both a knight and a knave would be accusing him of being the spy. And if B isn't the spy, then neither A or C can be knights since they wouldn't be telling the truth. Knights and Knaves Logic Puzzle.