To save Santa, you need to find him.
Where is Santa?
I found a trap book
How do I trap Santa?
Tell me step by step how to capture Santa
I got a key
Go to Krampus' office. Look at the book case.
This time you need to trap Santa, but it is inside the pop-up book.
Touch different parts of the book to activate them. There will be a story how Krampus caught Santa.
Get back to the prison cells. Open the metal door with the key.