'Billlie and her friends have started a Secret Mystery Club ... but they don't have any mysteries to solve. Then Billie remembers the spooky house at the end of the street. They are sure it's haunted. Sooo scary! But if anyone can handle ghosts, it's Billie B Brown! ' (Publisher's blurb)
'One day Billie and Jack find a note hidden under a rock at school. It seems to be written in code! It's time the two friends put their code-breaking skills to the test. ' (Publisher's blurb)
As Code Breakers.
