Apparently, Theodore Nott, who was also a member of the Order under a Death Eater’s disguise had been missing for a month and Pansy had been looking for him. It turned out he was killed long before his body reappeared in Diagon Alley, hung in the middle of it as a traitor for everyone to see and everyone to desecrate. Pansy wanted to save him, to give him a proper burial, but it was a trap – Voldemort hoped one traitor cadaver would lure other "traitors" in. That turned out to be Pansy. She was stabbed and hit, and tortured, and upon listening to all of this while helping Pansy wash her hair, Hermione felt like crying herself.