Figure[White to move]

This time try tracing the White rooks' possible moves through any other pieces, searching for interesting destinations. At first the e1 rook may look most promising, but in fact the one on a5 has the more intriguing potential. Follow its path horizontally through the White knight (at e5) to a square where the rook can give a check (g5). Again the question becomes whether the knight can vacate e5 in a way that creates a target on the other side of the check. 1. Nxg4 is the answer; if Black replies NxN, then Black’s knight ends up loose and 2. Rg5+ wins it after the king moves. This is almost identical to the previous position, of course, except that the rook’s move is horizontal rather than vertical.