Ocean, nine, from Brentwood has had a tough time. His younger brother Sky died two years ago and he needs a place to escape to when things get too much for him. He also has a new baby sister which he's excited about but his house has become pretty noisy! Ocean loves marble runs because they're like rollercoasters and one day he'd like to be a rollercoaster designer. He wants a marble run den where he can get away from it all and work towards his dream.

Brothers Alec and William are very proud of their Scottish heritage. And it's not just their family they're proud of, they think Scotland has a really interesting history and they want to celebrate it. The problem is that Alec and William live in a remote part of Scotland and there aren't that many kids around to play with, so they want a den to play in that looks like a traditional Scottish castle.