Teabing's Betrayal

At Westminster Abbey, Langdon and Sophie find a message from Teabing on Newton's tomb, luring them to the Chapter House. They go there, only to be trapped by Teabing himself, who reveals he is the Teacher. He explains that he orchestrated the murders because the Priory had decided not to reveal the Grail secret. He claims Saunière was a traitor. He demands Langdon help him open the cryptex, holding Sophie at gunpoint.