Why is Creon so surprised when the sentry brings in Antigone?
No one expected the that a family member, especially a woman, would be responsible for breaking Creon's edict. Antigone is Creon's niece and she is also engaged to his son. Creon would expect Antigone, of all people, to obey his wishes. Instead, Antigone says she is obeying a higher law, that of the gods. This puts Creon is a very difficult situation. So he follow through with his edict and put Antigone to death. This would mean Oedipus' would have only one heir left, Ismene, since her two brother killed each other and Antigone would be executed. It would also mean killing the woman his son loves. However, if he breaks his word, as a new king, people might lose respect for him and not believe him when he issues the next edict.