Complex sentence: The player and Ann Tickwitty must help the head priest to mummify Thutmose's body, after which they find Sir Vile hiding behind a piece of the wall depicting Amun Re and arrest him.
Split into simpler sentences: The player and Ann must help the head priest to mummify Thutmose's body. After Thutmose's body is mummified, the player and Ann find Sir Vile hiding behind a piece of the wall depicting Amun Re and arrest him.