Complex sentence: Lyra discovers that Coulter is the leader of the Gobblers, a secret Church-funded project, and flees to the Gyptians, canal-faring nomads, whose children have also been abducted.
Split into simpler sentences: Lyra discovers that Coulter is the leader of the Gobblers, a secret Church-funded project, which is abducting children. Lyra flees to the Gyptians, canal-faring nomads, whose children have also been abducted.