He pulled off the lid of the case for the third time, and the Dementor rose out of it; the room fell cold and dark --

"EXPECTO PATRONUM!" Harry bellowed. "EXPECTO PATRONUM! EXPECTO PATRONUM!"

The screaming inside Harry's head had started again -- except this time, it sounded as though it were coming from a badly tuned radio -- softer and louder and softer again. . . and he could still see the Dementor. . . it had halted. . . and then a huge, silver shadow came bursting out of the end of Harry's wand, to hover between him and the Dementor, and though Harry's legs felt like water, he was still on his feet -- though for how much longer, he wasn't sure. . .

Chapter 12