Complex sentence: The cloaked figure tracks the Joker to his hideout--an abandoned world's fair amusement park--and removes its ominous mask: it is Andrea, intent on avenging her father's death.
Split into simpler sentences: The cloaked figure tracks the Joker to his hideout--an abandoned world's fair amusement park. The Phantasm reveals itself as Andrea, intent on avenging her father's death.