Joseph, Sherrill. Botanic Hill detectives mystery #5

"Lenore Valentine Kirby's cryptic gravestone in a derelict cemetery beckons across centuries. The four Botanic Hill Detectives--Lanny, Lexi, Moki, and Rani--stumble upon a mystery revealed by the deceased woman's descendant, Mr. Nigel Kirby. Can the teens decipher Lenore Kirby's gravestone image and messages? Their unusual, present-day case, incorporating the life and works of Gothic horror writer Edgar Allan Poe, takes the four out to Ravenswood, the Kirby family's Victorian home. But one solution leads to more puzzles! Will the detectives successfully decode all the special instructions they discover to help restore Mr. Poe's reputation, damaged by a real-life enemy, and reveal to the world a priceless treasure? Come lend the squad a hand!" "--