Answer: Ismene refuses to help bury Polyneices.
At the beginning of the play, we are told that Oedipus, father of Antigone and Ismene, also had two sons, Eteocles and Polynices. After Oedipus died, it was agreed that each one of the brothers would take the throne of Thebes from one year to the next. However, after the first year, Eteocles refused to step down. This led to fighting between them, during which both brothers were killed. Creon is made king, and he decides that Eteocles should be buried in honor while Polynices should not be buried at all. Antigone dislikes this, and decides to take it upon herself to see that Polynices is buried as well. She tries to enlist the help of her sister Ismene, but she is not brave enough to defy the king. This greatly angers Antigone.