Complex sentence: The following day, Jake returns to the cave only to be followed by a bird watcher (Rupert Everett), who transforms into Jake's psychiatrist, Dr. Golan, and then reveals itself to be Mr. Barron.
Split into simpler sentences: The following day, Jake returns to the cave only to be followed by a bird watcher (Rupert Everett). The birdwatcher transforms into Jake's psychiatrist, Dr. Golan, and then reveals its true identity to be Mr. Barron.