MI5 needs a new electronics expert, and Peter Chapman is the one they want. After unexpectedly losing his lecturing job at the polytechnic, Peter is left with little option but to accept MI5's offer, and become Piglet.

Piglet is tricked into temporarily housing a recently defected electronics specialist. Agents are sent to kidnap and return her. However, they take Piglet's wife instead.

The team is assigned to monitor a couple suspected of transmitting information to East Germany. But are they watching the right people?

Piglet is the victim of mistaken identity, with potentially fatal consequences.

Piglet must use all his espionage skills to infiltrate an activist group and plant bugs.

The French have developed a top secret device for use on their military aircraft. During a test flight, the plane crashes. Everybody wants to get their hands on the device when the debris is recovered.

Sir Desmond wants to make budget cuts by amalgamating MI5, MI6 and other agencies. Piglet and his colleagues use their espionage skills to try to find the skeletons which might persuade Sir Desmond to reconsider.

A book 'The Coldest of Wars' is due to be published about 'Cold War' espionage. When Piglet 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 before it hits the shops.

Questions of loyalty are asked when a former agent returns and points the finger of suspicion at Maxwell.

All of a sudden, Piglet 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 KGB mole.

Which is better, MI5 or MI6? After a disastrous training exercise, Drummond is challenged by his MI6 counterpart to answer that very question.

MI5 has acquired a Russian decoding device, but it won't work. Piglet uses his electronics skills to try to understand why.

Piglet has been encouraged to get very close to a female KGB operative. What steps must he take to make sure his wife doesn't find out?

Piglet and his colleagues are attending a foreign Embassy reception. As they attempt to plant some bugs, terrorists storm the party and take guests hostage. Can Piglet and Dexter save the day?

Piglet discovers an arms stash in a remote farmhouse. When caught, he's taken to the manor house, and is surprised to find Drummond already there.

The Chinese have used advanced surgical techniques to create a perfect copy of Piglet.

Flint finds a new boyfriend, while Maxwell and Drummond prepare a promotional video.

Piglet is undercover in a hotel, when Sarah appears with her colleagues.