"Threats are vague. Blackmail is not," she answered. "I need to know that I trust you, Theodore." She listened to his explanation, nodding. "Fortunately, he's still thinking like we used to, and we shall have to use it against him.
"Speak to Potter, give him a list of these objects. Maybe he can try to obtain them, and he can put whoever owns that dreadful place under surveillance." She still remembered the damage that it caused when her Draco had insisted on using it to get the Death Eaters into Hogwarts. "If someone there is working for him, we can find him."
She tried again, and then called her house elf, asking for an envelope, parchment and a quill. "He's not going to give me the cure," she said, knowing that he wouldn't have gone to the trouble to hex them unless he wanted something. "And if he needs me, then he shall learn that I don't cower."
Narcissa put the message in the envelope and then wrote a simple message:
Only children play silly games.
She put the parchment inside the envelop and then outside she addressed it to 'Tom Riddle'. She handed it to the house elf. "Have an owl deliver it," she ordered before turning to Theo. "We shall know how important this is soon enough. Would you care for tea in the mean time?"