Colleen

“McGonagall came around as usual, collecting names of those who would be staying at school for Christmas. Harry, Ron, and Hermione signed her list; they had heard that Malfoy was staying, which struck them as very suspicious. The holidays would be the perfect time to use the Polyjuice Potion and try to worm a confession out of him. Unfortunately, the potion was only half finished. They still needed the bicorn horn and the boomslang skin, and the only place”
― J.K. Rowling, Harry Potter and the Chamber of Secrets