When estranged siblings Lindsay and Brad travel to Scotland at Christmas to reunite with their mother Jo, a big family secret is revealed.

16-year-old student Moira McKendry, gifted, popular and fun-loving, is found dead after a school party. The fatal head injuries indicate a violent crime. Moira's best friend, the introverted Hanna, was apparently the last person to see Moira alive. But Hanna can't remember anymore.