Mike Harding was due to be discharged after twenty two years service in the British Army. Several of those years were spent at Hereford with a Special Forces regiment. It was because of the skills he acquired while at Hereford that the Ministry of Defence was reluctant to lose him so instead of being discharged, he was offered an opportunity to join MI13, a covert department within the Ministry of Defence headed by Major Challenor, a former British Army officer.

Following a failed attempt by a Russian agent disguised as a bicycle courier, to successfully deliver a parcel containing ricin to the Victoria Street office of MI13, an obscure department within the Ministry of Defence, the man is sent to join the two other Russian agents already at large in Faslane, Scotland. Located at Faslane is Her Majesty's Naval Base Clyde, otherwise known as HMS Neptune, home to the UK's squadron of nuclear armed, nuclear powered submarines. The three Russian agents have been ordered by the Kremlin to poison the crews serving in the submarines, Should they succeed, they will prevent the boats from putting to sea and cause exceptional grave damage to the defence of the realm. When several Royal Navy personnel suddenly fall ill after coming into contact with an unidentified substance, the commander of HM Naval Base Clyde suspects a terrorist attack to be the cause. The admiralty immediately reports the problem to the Ministry of Defence who call upon MI13 to send an agent to Scotland. Major Challenor, officer in charge of MI13 sends Mike Harding, a former British special forces soldier now a deniable asset assigned to MI13, Harding will be aided by two former Metropolitan Police Special Branch officers, DI Annalisa Botelli and DI Dave Stephenson, both recently transferred to MI13. Challenor informs Harding there is no time for tea and biscuits over a cosy chat with a vicar, they are to find then terminate the perpetrators with extreme prejudice. .