Yaxley laughed jeeringly. Below, the fluffy silver cat patrolled up and down, and the Dementors stood waiting in the corners.
It was Umbridge’s lie that brought the blood surging into Harry’s brain and obliterated his sense of caution—that the locket she had taken as a bribe from a petty criminal was being used to bolster her own pure-blood credentials. He raised his wand, not even troubling to keep it concealed beneath the Invisibility Cloak, and said, “Stupefy!”
There was a flash of red light; Umbridge crumpled and her forehead hit the edge of the balustrade: Mrs. Cattermole’s papers slid off her lap onto the floor and, down below, the prowling silver cat vanished. Ice-cold air hit them like an oncoming wind: Yaxley, confused, looked around for the source of the trouble and saw Harry’s disembodied hand and wand pointing at him. He tried to draw his own wand, but too late: “Stupefy!”
Yaxley slid to the ground to lie curled on the floor.
“Harry!”
“Hermione, if you think I was going to sit here and let her pretend—”
“Harry, Mrs. Cattermole!”
Harry whirled around, throwing off the Invisibility Cloak; down below, the Dementors had moved out of their corners; they were gliding toward the woman chained to the chair: Whether because the Patronus had vanished or because they sensed that their masters were no longer in control, they seemed to have abandoned restraint. Mrs. Cattermole let out a terrible scream of fear as a slimy, scabbed hand grasped her chin and forced her face back.
“EXPECTO PATRONUM!”
The silver stag soared from the tip of Harry’s wand and leaped toward the Dementors, which fell back and melted into the dark shadows again. The stag’s light, more powerful and more warming than the cat’s protection, filled the whole dungeon as it cantered around the room.
“Get the Horcrux,” Harry told Hermione.
He ran back down the steps, stuffing the Invisibility Cloak into his back, and approached Mrs. Cattermole.
“You?” she whispered, gazing into his face. “But—but Reg said you were the one who submitted my name for questioning!”
“Did I?” muttered Harry, tugging at the chains binding her arms, “Well, I’ve had a change of heart. Diffindo!” Nothing happened. “Hermione, how do I get rid of these chains?”
“Wait, I’m trying something up here—”
“Hermione, we’re surrounded by Dementors!”
“I know that, Harry, but if she wakes up and the locket’s gone—I need to duplicate it—Geminio! There… That should fool her…”