A Court of Thorns and RosesChapter 4
Feyre Crosses the Wall
A massive faerie beast (Tamlin) bursts into Feyre's cottage demanding justice for Andras's death, invoking the Treaty and forcing Feyre to choose between death or crossing into Prythian.
Outcome
Feyre chooses to go with Tamlin to Prythian, leaving her family behind to fulfill the Treaty's terms.