Here the key line is the long diagonal where Black has a queen and two pawns lined up with his king; the cluster of king and queen alone should get you thinking about a pin. To the untrained eye the Black pawns on the diagonal might seem to scotch the idea, but you know better: it may be possible to avoid such pawns or get rid of them, turning the other piece on the line into a pinnable target. Start by looking for a piece of your own that can reach the line at issue. Here you see that your dark-squared bishop can get to e5 in one move—and that if the pawn on f6 were removed, Be5 would pin the queen. The pawn protects nothing that you can take, but again you can capture it: Rxf6 picks up a pawn, and now if Black plays QxR his queen is ready to be pinned with Be5 (the bishop takes protection from the rook on e4). Black plays QxB, and after White recaptures he has won a queen and a pawn for a rook and a bishop.