I’ve lost track of the logical flow of the following conversation between Lucius Malfoy and Harry.
And still, behind his back, Dobby was pointing, first to the diary, then to Lucius Malfoy, then punching himself in the head.
And Harry suddenly understood. He nodded at Dobby, and Dobby backed into a corner, now twistng his ears in punishment.
”Don’t you want to know how Ginny got hold of that diary, Mr. Malfoy?” said Harry.
Lucius Malfoy rounded on him.
”How should I know how the stupid little girl got hold of it?” he said.
”Because you gave it to her,” said Harry. “In Flourish and Blotts. You picked up her old Transfguration book and slipped the diary inside it, didn’t you?” (Harry Potter 2 [US Version]: p.336)[Bold font is mine]
N.B.: Dobby is a kind of servant of Lucius Malfoy, Harry’s enemy. He conveys the fact by gesticulating that Lucius is the culprit who gave Ginny a kind of jinxed diary. He punishes himself for the betrayal of his master.
To be honest, I can’t understand why I can’t understand. I was thinking it was because I didn’t understand “Don’t you want to know -”, and asked. But I still can’t get why Harry is saying “Because -”. It seems that they have a talk in a secret code.
How does the conversation progress? What reason is Harry conveying by saying because? I’d be glad if you could guide me through the conversation.