Friday the 13th: The Series (1987)

Season 3: Episode 2

Micki and Ryan get word of Jack's injury at the end of the preceding episode. They travel to Marie-Mere with Johnny Ventura to investigate and try to recover Lucifer's Bible. Asteroth uses the Bible to take control of Ryan, who must then kill an innocent child to fulfill the final prophecy that signifies Satan's arrival upon Earth. Ultimately, Jack recovers and he, Micki and Johnny manage to thwart Asteroth. However, the ritual turns Ryan into a 10-year old permanently. He leaves with his mother, and Johnny takes his place.