When the murder of a colleague is linked to a series of suspicious deaths, Detective Superintendent Greg Woods' team are tasked with solving the mystery. New to the team is Maria Barnes, whose besmirched character sadly precedes her. However Woods quickly discovers there is more to the detective sergeant than meets the eye: her skill level, knowledge base, and investigative talents far outshine his own formidable qualities... And why is the Secret Intelligence Service so interested in Barnes and the investigation? It's a race against time to stop the killer, but he's meticulous, cunning and ruthless. He leaves the police and intelligence service questioning if they are all out of their depth... When forces contrive against them, Woods' life hangs in the balance and for the first time in his career he risks breaking the rules... He and Barnes decide to go it alone to uncover who or what CXVI really is... The shocking truth lies at the heart of the Government and is trapped deep underground.