The Haunted Library Books in Order

When Claire’s classmate reports seeing a ghost during school-play rehearsals, Kaz hopes the apparition could be his missing mother. The young detectives investigate backstage, but persistent supernatural activity offers few clear clues about the ghost’s whereabouts.

Kaz and Claire take their detective agency’s first case after hearing that a neighbor’s attic is haunted. With assistance from Grannie, the ghost boy and his human friend examine the strange events and search for an explanation.

Separated from his ghost family when their home is demolished, Kaz meets Claire, a girl who can see spirits. Together they investigate a ghost haunting her family’s library, hoping the mystery might lead to Kaz’s missing relatives.

Claire’s friend reports mysterious activity that returns every day at five o’clock. Kaz wonders whether his missing brother is responsible, but searching the house reveals no ghost, leaving the detectives to investigate the recurring disturbances.

Kaz still hopes to locate his missing parents and older brother when Claire learns of a haunting at the fire station. The two detectives investigate the ghostly visitor, wondering whether this new case could reunite more family members.

After learning to pass through walls, Kaz explores a concealed room behind the library and discovers bottles, an envelope, and a ghostly doll. He and Claire investigate the room’s history while trying to identify the doll’s owner.

Strange sights and noises disrupt a girls’ club that meets in a tree house. Claire and Kaz investigate whether rival boys are responsible or a ghost is involved, while Kaz continues hoping to locate his missing relatives.

A family struggling to sell its house suspects a haunting is driving buyers away. Kaz and Claire investigate the elusive ghostly activity, hoping their latest detective case will also provide clues to more of Kaz’s missing family.

Kaz and Claire search for the ghost boy’s long-lost uncle, following leads to a bakery and movie theater. Along the way, another young ghost detective enters the investigation, adding a new connection to their family mystery.

While visiting Claire’s cousins in Seattle near Halloween, Kaz and Claire meet a library ghost whose family has disappeared. Their search leads into the city’s underground passages, where further supernatural activity gives the detectives fresh clues.