As Ben Baxter continues to write his diary, we find him faced with several more curious crimes and the odd mystery. He is helped as usual by his pal Johnny, his sister Katie and Chippy. Ben and Johnny return to being store detectives; this time, however, they have been invited back by the store manager. Knowing they have solved crimes in the past, the manager has offered to show them his store's crime prevention set up. However, things don't run as smoothly as expected, which leads to a certain amount of danger and excitement all round!
Soon after this, Ben's detective team gains a new assistant in the form of Millie. She is an ex-police sniffer dog who was injured during the course of her work. Although largely recovered from her injuries, the police decide she should be retired and rehomed. What better home to go to than Ben and Katie's, where she will be well-loved and possibly help sniff out the odd crime? She does indeed prove valuable in this respect.
When it comes to investigating a haunted room in a local vicarage, even Millie's hair is seen to stand on end. What on earth is behind this spooky business which we are told has been happening on and off over the last one hundred years?