Luke reveals to her that their father is Darth Vader and that he must defeat him personally.
Later…
Surrendering to Imperial troops, Luke is brought before Vader, and he tries to convince his father to return from the dark side of the Force.
Okay, what? Luke starts off wanting to defeat Vader, yet now he wants to redeem him?
Looks to me like a typo. Can easily be fixed by replacing defeat Vader with defeating the Emperor.