After walking away from Raven thinking she is a liar, the Teen Titans are later convinced she was telling the truth that her evil father Trigon lives and is coming to destroy the earth. Most hurt at the beginning of the story is Wally West, who is in love with Raven.
Raven is attacked by Trigon's servant Goronn, but the Teen Titans (once compelled by Raven after some hesitation) subdue the beast.
Trigon appears before Raven and expresses his disgust that she is weak and compassionate for humans, who he is ready to destroy (and does, a little, in Manhattan). In exchange for mercy for the Titans and the Earth, Raven agrees to join Trigon as he moves to conquer various dimensions.
The story continues in New Teen Titans 6.
The Justice League only appears in flashback.