All the ingredients just mentioned are in place again here. Find them and the solution is simple. White gives the flush check Rg7+, forcing Black to play KxR (otherwise his queen gets skewered). Then White plays QxQ+. The point: when you see the enemy king guarding one of its pieces, think about a check to drive it away; and be sure to include a look for check sacrifices that will draw the king out of position by making it capture away from the queen.