This time the search for the basis of a discovery leads you to the first rank. Black’s queen appears to have pinned White’s bishop to his rook; but if the bishop can vacate the rank forcefully enough, White can turn the tables and play RxQ. Indeed, everything is in place for a discovered attack except a suitable threat for White’s bishop to make. It can’t now threaten Black’s king; the bishop travels on dark squares and the king is on a light one. But the king can be dragged onto a dark square with QxR+. After the reply KxQ, White has the discovered check Bh6+, leaving behind his rook's attack on the Black queen.

Or you might come at the position from the other direction by just looking for checks you can use to move the king into a vulnerable position. White has two: Qxf7 and QxR. Qxf7 still leaves the king on a light square after KxQ. But if White instead plays QxR, the recapture KxQ leaves the king on f8. Now the c1 bishop would be able to give check with Bh6+; White next plays RxQ, taking the queen and netting a rook with the sequence.