Peter Chapman, an electronics professor at the Polytechnic, is followed by two MI5 agents (we find out later it's Dexter and Lewis). The agents at MI5 have had trouble figuring out how to use the technical equipment they're given for surveillance, and two higher-ups, namely Maxwell and Drummond, are impressed with Chapman's teaching credentials. So Peter is given a small incentive to join up - he's fired from his job at the Polytechnic! He interviews for the MI5 position and when they finally tell him what it's really about, he asks for a code name. Maxwell says he's been watching too many movies, but Peter is disappointed so they give him a code name: Piglet. Piglet's job is to assist in instructing the agents on how to use the equipment. Unfortunately, he inadvertently bungles a job in which Dexter and Lewis were trying to prevent Peter's supervisor from defecting to the USSR. So Maxwell and Drummond read Peter the riot act for messing up his first day on the job, but at the same tim

Peter starts having nightmares about being tortured by enemy spies. At the office, Peter is asked what he knows about a Dr. Volganyn. Peter has read a paper by this scientist theorizing about an invisible radio system - a completely undetectable listening device. The scientist, who is Soviet, is defecting and giving the secrets of the listening device to the British. Since the Russians know all the safe houses, the new guy, Piglet, is suckered into hosting this person at his house. Wondering what he will tell his wife, Sarah, he comes up with the story that the guy was one of his school classmates and that they played football together, but it turns out the defector is female. This creates some awkwardness between Peter, Sarah and Dr. Volganyn, whose first name is Nadia. Peter leaves the house briefly to pick up some lager, warning Sarah to be careful, but when he returns Sarah is gone. The Soviets, in an attempt to retrieve Volganyn, kidnapped the wrong woman. Lubenkov, an official wi

MI5 gets wind of a novel about to be published called ""The Coldest of Wars"" that's going to ""blow the lid off MI5"". When Peter reveals that his wife Sarah, who works for a publisher, has just been reading a manuscript by the same name, he and Dexter are ordered to intercept the manuscript before it is published.

Is Major Maxwell actually a spy for the KGB? Drummond is determined to find out - after all, if he is, Drummond gets his office, his position and a substantial pay rise...

All of a sudden, Peter has a drinking problem...and a gambling problem...and financial difficulties...and marital strain. What's going on? Well, Drummond has ordered him to put on the show as a ploy to see if Maxwell is a mole for the KGB.

After Dexter bungles a safe-cracking operation, MI5 and MI6 make a wager. MI5 must break into MI6's offices, open a safe on a specified floor in a specified room, and bring the contents to MI6. Drummond realizes they must hire a professional for this job - after all, he won't be losing the bet to his friend at MI6 - so he arranges for the release of a thief from prison, and Peter gets to babysit this man of dubious fashion sense and even more dubious principles while the ""caper"" is afoot. But is the bet on the level or is Drummond being manipulated?

After years of chilly relations with the Vishwani government, the Foreign Office (and MI5) are invited to the embassy for a formal evening, now that the government has changed hands (MI5 has been asked ""in the new spirit of openness"" to bug the embassy). Unfortunately, terrorists have other plans and besiege the embassy - with agents and their wives still inside. The wives, of course, have all been told something different about where their husbands actually work. Amidst this backdrop, Peter and Dexter must save the day without getting anyone hurt in the process.