Figure 2.2.8.4[Black to move]

Strictly speaking White doesn’t have any pieces that are loose, but his bishop at h6 is attacked once and protected only once, and by another White piece (the queen) rather than a pawn. In a sense that makes the bishop as good as a loose piece: if Black can attack the bishop and give check, the bishop will be lost; it will be attacked twice and protected just once, so BxB will result (White wouldn’t be able to recapture with QxB, because then Black would play QxQ). But all this assumes Black can get his queen onto a square where it can give check and attack the bishop at the same time—viz., h4. Black’s own knight at f6 stands in the way. The trick is to vacate the knight from the square in a way that forces a time-consuming response from White; so look for captures the knight can make. 1. …Nxe4 attacks White’s queen and can’t be ignored. White responds with 2. f3xN or 2. NxN, NxN; 3. f3xN. Either way, Qh4+ then wins the bishop and Black nets a pawn with the sequence.