Chess in 40 SecondsThe Caro-Kann smothered mate
White to move. Mate in 1.
Snort moved his knight to f6 and boxed in his own king. Mate him.
Hint
His e7 pawn can't move — your queen is lined up behind it with his king.
Answer
Nd6# — Smothered mate! Black's own pieces block every square.
The idea
Smothered mate: when a king is surrounded by its own pieces, one knight can finish it.
This chess trap is one of 30 quick puzzles in the Chess in 40 Seconds trainer: find the move on the board, get a hint if you're stuck, and learn the idea so you never fall for it in your own games.