Death in the Fog — Mignon G. Eberhart

Fog and sleet make driving hazardous in the Chicago traffic. When Katie Warren momentarily stops her car on Michigan Boulevard, she hears a shrouded voice say, “I won't eat grape hair, nor yet glocks.” The image of grape hair is sinister enough to stick in Katie's mind. Steering through bad weather, she eventually reaches Aunt Mina's gloomy mansion -- and then something terrible happens.