The protagonist, Emerson Kent, is a seasoned CIA operative who has spent years carrying out covert operations, including assassinations and other "wetwork" assignments. However, his latest operation leaves him questioning his moral code, and he is subsequently given a psychological evaluation that recommends he take a break from field work.
Kent is then assigned to a remote location in England, where he is to protect a code announcer named Katherine, who works at a "numbers station." Such stations are used to broadcast encoded messages to operatives in the field; in this case, the station is being used to communicate with agents in Iran.
Things quickly go awry when the station is attacked by unknown assailants, and Kent and Katherine are forced to go on the run. As they attempt to evade their pursuers, they also begin to unravel the mysteries behind the attack and the true purpose of the numbers station.
One particular twist in the plot involves the revelation that the numbers station has been broadcasting a false message for years, intentionally misleading the agents in Iran. Ultimately, Kent and Katherine must work together to ensure that the correct message is sent and that their own lives are not lost in the process.
Overall, The Numbers Station is a taut, suspenseful thriller that grapples with issues of morality and loyalty, all while keeping viewers on the edge of their seats.