Clad in their red high-school blazers, three friends become amateur sleuths who decipher an intricate puzzle leading to the priceless Ring of Rocamadour. Dramatic Sophie, brainy Margaret and artistic Rebecca attend the upper school at St. Veronica’s all-girls’ school in Manhattan, where they encounter the elderly, eccentric Ms. Harriman who lives next door. Ms. Harriman enlists the sympathetic trio to solve an elaborate puzzle her archaeologist father created 20 years ago. As the girls discover, the clues refer to objects or places in St. Veronica’s and challenge their knowledge of religion, classical languages, math, literature, philosophy and art. For each clue solved, another is provided. As the girls get closer to the ring, they realize they aren’t alone in their quest. Sophie’s chatty, melodramatic first-person, present-tense narration provides comic relief to the pseudo-gothic tone, inviting readers to crack the clues while the girls use their wits and spunk to pinpoint the ring’s location. Three plucky, clever heroines and one very intriguing puzzle equal lighthearted adventure with a modern twist. Move over, Nancy Drew! (diagrams) (Mystery. 10-14)