Young Derek Lestrange, Mrs. Bradley's grandson, is in need of a scrapbook to complete a school assignment, and finds just the thing in the form of a heavy diary that belonged to an earlier tenant of the house his grandmother has rented. Asking permission to use the mostly blank book, the boy hands it over and, upon examination, Mrs. Bradley concludes that Derek has found the diary of Bella Foxley, a rather disagreeable woman who was accused of murdering her cousin some years ago. Intrigued, the detective reads through the journal entries and begins to investigate the events surrounding Bella's tragic life.

For starters, Bella Foxley's wealthy aunt died under very peculiar circumstances: she choked to death on grated carrot that Bella had prepared. But Aunt Flora was never particularly health-minded, and grated carrot seems an odd request. Around this time, two boys escaped from the reform institution where Bella Foxley worked, and rumor had it that she had a hand in their disappearance. Finally, the arrival of cousin Tom and his wife Muriel was doomed to tragedy: paranormal investigator Tom fell out of a top floor window of a supposedly haunted house, and he had to be hospitalized. He barely made a recovery when he fell out of the same window again, this time with fatal results. With no alibi and a possible motive that Tom was blackmailing her, Bella is tried for her cousin's death, but is acquitted and moves away to another village with her sister, Tessa. All goes well until one of the sisters is found drowned in a nearby pond.

Interviews with widow Muriel, housekeeper Miss Hodge, and the warden of the boys institution raise as many questions as they answer; Bella's diary carries a number of inconsistencies and mistakes; and the missing boys never resurface again, ever. Mrs. Bradley is convinced that answers lie within the haunted house, and, so thinking, she exhumes this case from the past by moving into the tragic place and persuading the dead to unburden their secrets to her.