The Secret of Willow Lane — Virginia Rose Richter

Two eleven-year-old amateur detectives set out to solve the mystery of a deceased neighbor's missing will and to identify a stranger snooping around the mansion where the will is thought to be hidden. What begins as an excuse to use their new detective kit turns into a frightening experience that ends with the girls running for their lives. This is the first book in a new mystery series recommended for ages 9-12.