Beware of leaving your pieces lined up on the same rank. They may get skewered, as has happened here to Black: White saw Black’s queen and knight so aligned, and thus played his rook to c6 with protection from his bishop on f3. There is no room to interpose anything, and Black has no way to give check with his queen that does not lose it on the spot. And this time he has no mating threats. Now what options remain? If you are in Black’s shoes you mustn’t allow the threat you face to distract you from your usual tasks, including a scan of the lines leading away from White’s king. In this case the scan reveals that White’s rook can be pinned. Black plays Rc8 and the skewering threat is over. White cannot legally play RxQ; he can play RxR, but then Black recaptures RxR+ and it’s a wash.