Shockwaves are running through the heart of government today as a renegade MI5 officer goes on the run today after assassinating the head of the armed forces.

	View highlights of Episode 10

Tom received a tip-off from Christine Dale. She'd accidentally got hold of information that a known American assassin had been sent to Britain by the Iraqis. Apparently the CIA were determined not to let MI5 know, but she felt if there was a risk of the assassination of a major British figure then Tom ought to know. But he mustn't tell anyone else.

He secretly talked Zoe and Danny into helping him. Zoe was immediately uncomfortable with keeping secrets from Harry, and suspicious about the whole thing, none of it seemed to add up, and Tom was behaving very strangely. So Danny followed Tom, and stumbled upon evidence that Tom was preparing a legend secretly. Zoe and Danny began to suspect that Tom had gone bad.

Tom managed to win a last bit of trust out of Zoe and Danny and they followed a trail of evidence to a deserted farm in Suffolk. There they were ambushed and chained up. Danny confronted Tom about the legend, but Tom denied knowing anything about it, claiming he was being set up.

Danny and Zoe were drugged, and when they woke Tom was gone. The rushed back to the office and told Harry everything. Meanwhile Tom was tricked into putting his fingerprints on a gun, and the mysterious CIA man admitted he had a personal grudge against Tom and was out for revenge.

When Tom came to he rushed to the nearest house, and phoned the office, warning them there was a planned assassination and his fingerprints would be on the gun. It was too late. The assassination had already taken place, and the team were convinced Tom was to blame. He was desperate to prove he'd been set-up and persuaded Harry, Tom and Zoe to come and meet him.

The set-up had been too good. There was no way he could persuade any of the team of his innocence. Tom was cornered and as Harry threatened to call in back-up, Tom took the only way out. He shot Harry and ran. When he reached the beach he just kept going, and swam out to sea and an uncertain future.

Do 'Clandestine Operations' really exist within CIA?
Any secret intelligence organisation is bound to have as many internal secrets as external. The easiest way to ensure secrets remain secret is to ensure as few as possible people have access to information. If information is released only on a need-to-know basis there are far fewer chances of leaks. Although we are in an age where agencies such as the CIA and MI5 are at pains to project an image of greater openness, the public are only aware of a very tiny amount of what goes on. There are always rumours flying around about the CIA being involved in any number of secret operations, assassinations and conspiracies. From CIA paramilitary groups fighting in Afghanistan to faking the moon-landings, how much of this you choose to believe is entirely up to you!

What would happen to an MI5 officer who went bad?
Disloyalty to your country is treason, and this is considered to be an extremely serious crime. So serious in fact that it still held the death sentence until as late as 1998. However in practice it has been a very long time since anyone has been punished in such a severe manner. The last person to be executed for treason in this country was William Joyce in 1946 for his support of the Germans during WWII.

Less than 10 years later the Cambridge spy ring was began to be uncovered. However none of those involved were brought to justice, and most were able to flee to Russia to begin new lives there. Even when Anthony Blunt was finally connected to the group in 1979, he was stripped of his knighthood and many of his privileges, but there was no conviction.

A traitor who received rather harsher treatment was Michael Bettaney. He had been recruited to the MI5 in 1982 as part of a drive to recruit more ordinary people as agents. He immediately proved to be utterly unsuitable for the service, but for some reason was retained. He was determined to become a double agent, although he cut such an unconvincing pose that the KGB thought MI5 were trying to set them up, and so immediately reported Bettaney's approaches. In 1983 he was sentenced to 23 years in prison, although he actually only served 14 years of his sentence.

More recently, in 2000, 87 year old Melita Norwood was revealed to have been a spy. She had spent years passing scientific and technical information on to the KGB and received their highest decoration, 'The Order of the Red Banner'. She was only uncovered when an ex-KGB officer released her files. It was decided not to prosecute her because the only real evidence of her activities came from a KGB file, and the case was unlikely to stand up in court.

Nanotechnology
Most listening devices work by transmitting the sounds they pick up on radio waves. This would suggest that the transmissions could be picked up and recorded well away from the scene. This would indeed be possible if the signals were as strong as a normal radio transmission, but a bug sending out a signal as strong as this would be extremely easily detectable. To remain hidden the signal must be much weaker, so the listening post must be situated as close as possible to the transmitter. This is why vans are often used to park close to the bugs. These vans will often also be equipped with concealed cameras, so the spies inside can keep a really close eye on the whole area.

Lock Picking
For every different type of lock in existence there has to be a specialised way of opening it. The most common type of lock is the pin tumbler. Inside one of these locks is a range of pins which must be pushed into the right position to be able to rotate and open the lock. When you look at a standard door key, you'll see that it has a range of notches along the edge. These correspond to how the pins should be positioned, any other key would position the pins wrongly, and fail to turn the lock.

A lock-picker will use a pick tool to carefully nudge each pin, one by one, into the appropriate place. It sounds simple, and the theory is very simple. However, the practice is a highly skilled technique. It takes a lot of experience and knowledge to recognise the sounds and sensations that mean the pins are gradually nudging into the right place.

Copy Camera
A copy camera is a camera specifically designed to take photographs of documents. A regular camera can be used for this purpose but it is difficult to ensure that all the writing stays in focus and legible. While a photocopier does the job perfectly well in an office, a spy working undercover would need something considerably more portable and discreet.

To copy text effectively all you need to do is ensure that the camera is correctly focussed on the document. This can be achieved by setting a fixed lens and focus in the camera. With no adjustable settings, if the camera is always held at a set distance from object results will always be consistent. To this end most copy cameras will include a device for ensuring it is positioned correctly.