Checkmate patternsHook mate
A rook, knight and pawn form a chain of defenders shaped like a hook around the enemy king.
How it works (spoiler)
A chain of defenders shaped like a hook: the pawn defends the knight, the knight defends the rook, and the rook checks from right beside the king. The pawn is what makes it work — the king stands next to the knight, so without it the king would simply take the knight. The king’s own pawn seals the last square.