You see Black’s king and queen on the seventh rank, of course, and realize this is an opportunity; if there is a way to make a pin or skewer out of these materials, you must find it. White’s Rc7 fails to create a working pin because the rook has no protection against QxR. But an examination of every check White can give turns up Qxh7+. This has great promise, as it seems to skewer Black’s king to his queen. The hitch is that the king can move to e6, giving the queen protection. (A king and queen with one square between them often will present this problem.) White needs to stretch the two Black pieces a little farther apart. Last time we saw this done by attacking the king, causing it to move farther from the queen; this time we can try attacking the queen first, causing it to step away from the king. White plays Rc7, and as noted above Black must play QxR to save his queen—which then, however, has been moved beyond the reach of his king. Qxh7+ now skewers and wins Black’s queen in trade for the rook White sacrificed.

Notice a key point about these preliminary attacks used to drive apart the pieces meant to be skewered: in each case the attack has been made on the same line as the planned skewer, thus requiring the enemy piece that performs the recapture to stay on that line and preserve the alignment that makes the tactic possible. That isn’t always how it has to work, but it often is.