Book 4

The Five O'Clock Ghost #4

by Tomie dePaola

Published 10 March 2015
Kaz and Claire are back for a timely mystery in this adorable series by Edgar Award winner Dori Hillestad Butler!
 Kaz and Claire are called in for another ghostly mystery, and this ghost is always right on time. When Claire's friend tells the young detectives about his five o'clock ghost, Kaz wonders if it could be his own missing brother, Little John. Kaz and Claire search the house up and down, but they can't find any trace of Little John--or any other ghost. Yet when five o'clock comes along, the strange occurrences come back again...

Book 5

The Secret Room #5

by Tomie dePaola

Published 11 August 2015
Now that Kaz can finally pass through walls without feeling all “skizzy,” he can go explore Beckett’s secret room at the back of the library. What he finds there is a mystery he never expected!

Book 6

The Ghost at the Fire Station

by Tomie dePaola

Published 3 November 2015
When the fire station's new dog, Sparky, finds a ghost at the door of the TV room, Kaz and Claire investigate, hoping the ghost may be one of Kaz's relatives.

Book 6

With a lot of searching and a lot of luck, Kaz has found his dog Cosmo, his little brother Little John, his grandmom, and his grandpops. But what about his parents? Or his big brother Finn? Will he ever see them again? Kaz wants to keep looking for his family, but when Claire hears about a ghost at the fire station, Kaz knows it’s a case for C & K Ghost Detectives!

Book 7

A group of girls in Claires town have noticed strange sights and sounds coming from the tree house where their club meets. Is it a rival boys club trying to scare them away? Or is it a ghost? The girls ask Claire to tackle the mystery--and Kaz hopes to finally find the rest of his missing family members!