You have been taken to the Chamber of Secrets and a warning has been written in blood on the wall of the castle. Regulus reads it: "Her skeleton will lie in the chamber forever." After he hears it's you that has been taken, he realises just how much he cares about you and he hurries straight to the chamber entrance in the girls' bathroom. He then reaches the very chamber through the underground channels leading there only to find your still body laying on the floor of the chamber.