Being friends with a super sleuth isn't easy, especially when she's nine years old and four feet tall. But for 11-year-old aspiring writer John Watson, being friends with Shelby Holmes is just the adventure he's looking for.

In the few weeks since moving into Harlem with his mum, Shelby has been training John in the art of observation – a skill that comes in handy on the very first day of school. John's new teacher, Mr Cobb, is acting suspiciously, and Shelby knows this is a mystery worth investigating. Something important has gone missing, but as Shelby and John dig deeper into the mystery of the Cobb caper, they discover that there may be someone unexpected involved. Could Shelby Holmes have finally met her match?

Girl power comes to Baker Street in a book that's perfect for fans of Frank Cottrell Boyce and Robin Stevens.