Charlie Chalk (1988)

S01E06 The Mountain That Moaned

Arnold is convinced that the mountain emits a moaning sound, and he proves his theory during an adventure with Charlie and Lewis. The trio embarks on a journey to the mountain's base, tracing the eerie sounds through its dark caves and hidden underground lakes. Their exploration leads them to discover Bert, a solitary monster who has been stuck inside the mountain for far too long.