It's the beginning of 1957, and Rosa Reed takes a much needed break from her thriving private-investigative work by joining her cousin Clarence and Aunt Louisa for a weekend getaway at the Black Stallion Dude Ranch near Santa Bonita, California. Newly single and ready for a fresh start, all she needs is time on the trails and cuddles from her tabby cat, Diego. The peace and quiet of ranch life is soon disrupted when a horse returns from a trail ride without its rider. When foul play is determined, Rosa finds herself thrust once again into a murder investigation alongside the handsome detective Miguel Belmonte. Suspicion falls on many of the guests-the failed investment banker, the laundromat owner, the heiress, and, to Rosa's dismay, her own cousin Clarence. Can Rosa prove her cousin's innocence before the cows come home?