Eustace: A Paranormal Adventure (Allie's Ghost Hunters series)

After Allie's last experience with a ghost, she thought she was finally free of phantoms in her life—but that was before she went on a school trip to Hill End and found herself investigating several more of them. First there is the ghost of Granny Evans, pacing around the museum. Then she comes upon Eustace Harrow, possibly the ghost of a baby long dead, smashing things up in Taylor's cottage. When two of her classmates disappear, Allie realizes that things have gotten much more serious, and she must take action.