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.

Jonathan Pine is pulled into a dangerous world after he's approached with details about a secret arsenal of weapons set to be sold by a British business magnate.

Angela Burr persuades Jonathan to work undercover for her clandestine operation, and he immediately starts to create a false identity to get close to Richard Roper.

As Jonathan becomes more involved in Roper's life, he must contend with a suspicious Corkoran; 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.

Jonathan puts on an impressive display to persuade Roper of his loyalty; Burr finds her operation, and herself, under threat.

As Burr faces questions and drastically-reduced resources, Jonathan is pushed to the limit.