The morning after the party, Arthur was gone before anyone came down and Bridget left soon after the children awoke. They would not be back before the end of summer, and the house was once again the children's own.
They spent the morning on the concealed door in the trophy room and got nowhere with it. Nettle left for the market, and the three of them were still arguing about the door when they heard movement in the foyer. Three masked wizards walked into Noxley Hall.
Otto petrified the first before he had crossed the hall. Caoimhe blasted the second back into the planters, and Finlay petrified him where he landed. The third was not fighting at all. He was staring at a small brass instrument in his palm, and when he finally looked up he told everyone to stop.
He reached for something inside his robes, and Caoimhe summoned it out of his hand before he could produce it. It was a Ministry badge. Ambrose Tuft, Improper Use of Magic Office. He put his wand away and told them, at some volume, that he had every scrap of evidence he needed and that they would be hearing from the Department shortly, and then he and Caoimhe began shouting at one another in the wreckage of the entrance hall.
While they shouted, Otto slipped a subtle Legilimency into the man's mind and found it wide open. Months ago Tuft had overheard Tobias and Rafael talking about three children the Trace could not find. He had been investigating them ever since, alone, and had hired the two wizards now petrified on the floor to stage an attack for one purpose: to see whether the children would cast, and whether anything would register when they did.
Otto also found something else in there, a small and mortifying memory of Tuft as a young man, caught by his own father mid-waddle between stalls in a lavatory that had run out of paper. Otto mentioned it aloud, mildly, as something his father had once told him. Tuft went scarlet, collected his hirelings, and left.
They had Nettle write to Arthur about lawyers. Then Otto went back to the door and kept at the old elf, gently and relentlessly, until Nettle gave it up: the password was the Noxley family motto, in Latin. Order is mercy.
Below the trophy room they found a torture chamber with blood still on the floor, and past it an alarmed corridor ending at an enormous vault door, sealed with a key that Arthur and Bridget carry on their persons and never set down.
They came back up with a great many questions, and an owl was waiting. A summons: a hearing in two weeks, on a charge of improper use of magic. The punishment sought is expulsion from Hogwarts.