The children were in the cellar. They wanted to find a secret tunnel.

This story is short story.

The children go to the cellar, they wanted to find secret tunnel. But, they didn't find it. 

At that time, Kipper found the magic key, so they went to Biff's room and went on an adventure.

They went underground. It's big. They went down. Elves lived in the tunnel. They were very shy, so they didn't  greet the children.

Children didn't see the elves. They were afraid at the beginning, but Kipper had them all laugh, so elves came out and say hello.

Elves were sad  because they had no work, so children helped them to paint some signs and build the store. Elves appreciated to the children.

Underground Adventure. (2003) Roderick Hunt  Alex Brychta.