What happened to all of Santa's letters?
Why is Santa feeling a bit sad?
You'll be helping Simon get to the bottom of these mysteries in his latest Christmas adventure.
Make sure you're rugged up, because it all happens on Simon's favourite Christmas spot, Finland! (After all, Santa does live there)
Simon's latest Christmas adventure starts on this amazing train in Finland.
Click HERE for a super interesting page with lots of pictures of the actual train, and a description of taking an overnight trip on it.
It's the Polar Express in real life!
Feel like colouring some Christmas trains? This is an excellent free page.