Billie and her friends have started a Secret Mystery Club! There's just one problem - they don't have any mysteries to solve. But then Billie thinks of the spooky house at the end of her street. She has always wondered who lives there. Is it a witch or a ghost? It's up to the SMC to find out!
Billie and the Secret Mystery Club have found a mysterious note - in code! What does it say? And who could have sent it? One thing's for certain: it will take all the skills of the SMC to solve this mystery.
The school principal has given Billie and the Secret Mystery Club a very important mystery to solve. Many years ago, a time capsule was hidden somewhere in the school, and it's up to the SMC to find it!