Dori Hillestad Butler

Investigating a classmate's claim that he saw a ghost backstage while rehearsing for the school play, Kaz and Claire, harboring suspicions that the ghost may be Kaz's mom, discover compelling evidence of otherworldly activities.

While searching for his mysteriously lost human family, Buddy the dog is adopted by another family and helps solve the mystery of their missing boy.

"When ghost boy Kaz's haunt is torn down and he is separated from his ghost family, he meets a real girl named Claire, who lives above the town library with her parents and her grandmother. Claire has a special ability to see ghosts when other humans cannot and she and Kaz quickly form a friendship."--Amazon website.

Soon after Claire is called on to investigate a new case, her ghostly partner Kaz is reunited with his brother, Little John, who joins them in searching for the cause of strange phenomena that occur each afternoon at five o'clock.

When Buddy goes to school to become a therapy dog, he ends up helping figure out who pulled the fire alarm instead.

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!

When King's favorite blue ball goes missing, he and Kayla must put together clues to figure out where it went.

Mr. Summerling has left Marly, Sai, and Isla a set of brand-new clues to follow, including tickets to the mysterious Summer Island, where they hope to finally discover what lies at the end of the treasure hunt.

Trying to communicate with his human owner (and detective partner) can be frustrating for King the golden retriever as he uncovers clues in a missing dog case.

Mr. Summerling, Marly's neighbor, talked about being a treasure hunter, and news of his death has brought Marly into a treasure hunt of her own. In his will, Mr. Summerling left a treasure for Marly and two classmates, Isla and Sai. They barely know each other, but they have to work together with a series of riddles, puzzles, and clues to find the treasure.