Leeds, 1954: When enquiry agent Dan Markham takes on a case for Joanna Hart, she simply wants to know if her husband Freddie is being unfaithful. But when Freddie Hart is killed, Markham suspects someone has set him up. Former Cold War spy David Carter is pulling all the strings. Ruthless and professional, he's built himself an empire in Leeds and won't take no for an answer. Suddenly Markham finds himself battling to keep both his client and himself alive and is forced to employ the rusty skills he acquired during his National Service in military intelligence. But are they enough?