"Y" Is for Yesterday is the twenty-fifth and final novel in the "Alphabet" series of mystery novels by Sue Grafton. Grafton intended to write a Z novel, but she died before she was able to do so. It features Kinsey Millhone, a private detective based in the fictional city of Santa Teresa, California. The novel, set in 1989, finds Kinsey getting pulled into a decade-old case involving a sexual assault at an elite private school. The novel, published by G. P. Putnam's Sons, was released in the United States on August 22, 2017.