Maggie Brooklyn is distracted from solving the mystery of who is out to sabotage the new sweet shop in the neighborhood because her new dogsitting job has her and her twin brother Finn spending time in what may be a real haunted mansion.

Life is confusing for seventh-grader Maggie, who must track down a missing person and find out who is behind a string of dog eggings at the local dog run, while also dealing with issues involving her brother, two of her friends.