A Dark Christmas is set nine years after the events in The Siamese Connection. Martin's daughter Nina is now nine and his eighteen-year-old adopted Cambodian son Hon is a musical prodigy. The boy's amazing talent was instantly recognizable the first time he sat down on a piano bench. He is rehearsing for his first album to be followed by a world tour.

As Christmas rapidly approaches, things become tense in the LaRue household and in the studio as Hon's mysterious French girlfriend Juliette arrives - commanding more and more of Hon's precious time.

Tragedy strikes on Christmas Eve, bringing Martin and Ramonne together once again to face, perhaps, their greatest and most powerful modern enemy.