Sabrina and Daphne Grimm have been in and out of foster homes for a year and half since their parents disappeared. The authorities say they have located their grandmother, but it can't be true because their father said she was dead. When they meet Mrs. Grimm in Ferryport Landing, they regard her as odd, yet kindly, though Sabrina is suspicious of her motives. When Mrs. Grimm starts to tell them the Grimm family is part of the fairy-tale world and the 'everafters' live in Ferryport Landing with no means of escape, they are baffled. It is the Grimm's duty to keep them all safe and away from human eyes.

When Mrs. Grimm and her faithful companion, Mr. Canis are kidnapped, it is up to Sabrina and Daphne to read the clues and rescue them. Along the way, they encounter many fairy-tale characters, such as Mayor (Prince) Charming and his bumbling police force, Hamstead, Boarman, and Swineheart (the three little pigs)...not to mention Jack, of bean climbing fame, or Puck and his pixies straight out of a Midsummer's Night's Dream. It is up to the girls to figure out who is the bad guy in enough time to rescue Mrs. Grimm. The Sisters Grimm: The Fairytale Detectives is full of action, magical characters, and a race to thwart evil in time.