该剧改编自真实事件，一名军情六处的双面间谍和女儿被投毒，与他们同处一个小镇的人都身陷危险之中，警方需要竭尽全力保护他们。

Agatha opens her own detective agency, but potential clients aren’t exactly breaking down the door of her new office. In search of new business, Agatha and James visit Ivy Hall, a house said to be haunted since the English Civil War. Are the strange sounds and unexplained footsteps heard...

Agatha's in need of a well-earned break and with Christmas just around the corner it looks like the perfect opportunity to relax. When she receives a letter from an old lady begging for protection, she can't help but spring into action.