The Black Phoenix

The Black Family Tragedy was a well known story in the Wizarding World. The simultaneous kidnapping of eleven children is obviously an event that's hard to keep a secret. The fact that the abduction case is so famous is most likely why Hermione came across the article almost immediately when she started her roam through the library.

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In the dead of night, a stranger penetrated the wards around Malfoy Manor. Eleven of the thirteen children in the house were taken. Nine year old Nymphadora Black and one year old Draco Malfoy-Black were the only children to escape abduction, being saved by a house elf who caught the intruder in the act. By the time the elf was able to wake the adult occupants of the manor, the children and mystery wizard were gone.