At the end of the film version of Harry Potter and the Chamber of Secrets, Harry tricks Lucius Malfoy into giving Dobby a sock. Since this means that his household servant is no longer under his control, this understandably causes Lucius some annoyance. He pulls out his wand and begins to incant a spell "Avada..." before Dobby steps in and zaps him. Avada Kedavra is known as the 'killing curse'. Using it supposedly results in your immediate transfer to Azkhaban for a life sentence. Was Lucius seriously about to kill a twelve year old child with an unforgivable curse, directly outside the Headmaster's office, with witnesses around?