The Angel: Season 1, Episode 15

1 - 15: The Prodigal

Kate's father, Trevor Lockley, gets involved in a demon drug smuggling operation and he's soon in over his head. When a demon high on drugs attacks the subway, Angel begins investigating and quickly discovers Trevor's shady dealings. He tries to warn Trevor, but it's too late. When Trevor is attacked, Kate blames Angel for not doing more. Meanwhile, through flash backs, Angel's own father is introduced, Angel's past as a human is shown and Angelus is born.