Ruby Sans’ world is turned upside down when she discovers she is the sole living heir of an estranged aunt. Overnight, Ruby inherits a rare green diamond and finds herself a co-owner of a racehorse with an intriguing trainer carrying a shadowy past. As Ruby digs deeper into her new horse’s stats and his trainer’s track record, she soon discovers that she is in a race jockeying to find her best friend’s killer while uncovering the secret behind a slew of suspicious racehorse deaths.