Ultimatum

After helping to avert a deadly attack on London, Luke Carlton has been welcomed onboard as a full-fledged member of SIS and is assigned the role of case officer running agents. He is sent undercover into Iran to turn and recruit an officer in that country's infamous Revolutionary Guard Corps. The word is that a conservative group within the IRGC doesn't like the direction postrevolutionary Iran appears to be taking and are planning something big to embarrass their own government and frighten the country's new allies in the West. The intelligence services need to find out who and what, and fast, but then a senior British government minister on an official visit to Iran goes missing, and his close protection officers are found murdered.