Black has just moved his queen out where it can attack White’s queen. White’s queen is loose; Black’s queen has protection. White can move his queen, protect it, or play QxQ, but it would be rash to do any of these things too quickly. Think more aggressively, considering how Black’s queen is protected and whether anything can be done to undermine its security. What you should see is not just that the queen is guarded by its knight, but that the knight is attacked by White’s bishop. BxN won’t work, as it is met with QxQ. The significance of the bishop, rather, is that it also is aimed through the knight at a square adjacent to Black’s king. If the king could be moved over, the knight would be pinned—and then it might as well not exist so far as the Black queen is concerned. How to move the king over? With a check (and sacrifice): Rd8+. Black is required to play KxR (or Ke7), which brings the king into line with the knight and suddenly leaves Black’s queen without a defender. Now White plays QxQ and wins the queen without a recapture. (Black could not reply to Rd8+ with NxR, of course, because his c6 knight is pinned.)

Now of course another way to see the idea here is to experiment with the consequences of any checks you can give. White only has two, and one of them is Rd8+, requiring Black’s king to move. When you make the enemy king move, ask whether any fresh pins have appeared; here this leads you to the f6 knight, and you ask not only whether you can take the knight but whether its paralysis has consequences for anything it is supposed to protect—like Black’s queen.

This position is an example of the point made in the previous frame regarding forcing moves. Suppose Black’s king already were on d8 (because White played Rd8 a move earlier), and White’s bishop were on, say, e3. If the bishop went to g5 to pin the Black queen’s guard, nothing would come of it; it wouldn’t be a forcing move, so Black would be free to move his queen to safety—or, here, to play QxQ. But using a check sacrifice dictates Black’s move in reply and leaves him no time to prevent White from playing QxQ once the knight is pinned by Black’s own hand.

For the sake of completeness notice that White has another good pinning possibility here, too: 1. QxQ, NxQ; 2. Re1—and now White’s rook pins the knight on e4. Black can rush a defender to the knight’s side with Bf5, but then White can add another attacker with f2-f3. The knight will be lost. But it’s even better to win a queen for a rook as you do with the primary sequence. You might have seen this second idea first, though, and in that case the position shows the importance of looking beyond the first good tactical move you see. There may be something even better.