After being approached with details about a secret arsenal of weapons set to be sold by a British business magnate, hotel night manager Jonathan Pine is pulled into a dangerous world.
Angela Burr persuades Jonathan to work undercover for her clandestine operation, and he immediately goes about creating a false identity in order to get close to Richard Roper.
As Jonathan becomes more involved in Roper's life, he has to contend with a suspicious Corkoran, while the validity of Burr's operation is questioned by superiors.
While Jonathan takes advantage of Corkoran's instability and agrees to act as frontman for Roper, Burr's operation receives an unexpected boost, but forces from above are determined to stop it.
