第 3 季 共 10 集
播出时间：2004年10月12日
第 1 集 Project Friendly Fire
播出时间：2004年10月12日
Tom Quinn has disappeared after shooting his boss Harry Pearce. He also stands accused of assassinating the Chief of Defence Staff. Chairman of the Joint Intelligence Committee Oliver Mace uses this a pretext to launch a punitive investigation of MI5. Zoe, Danny and the team must prove Tom innocent and save the service from government takeover.
第 2 集 The Sleeper
播出时间：2004年10月19日
Harry reawakens sleeper agent Fred Roberts, a renowned chemist and family man. As Fred becomes more deeply involved with deadly terrorists, Tom has a crisis of conscience which could jeopardise his career.
第 3 集 Who Guards the Guards?
播出时间：2004年10月26日
Danny and the team must uncover the truth behind an assassination attempt on a famous novelist.
第 4 集 A Prayer for My Daughter
播出时间：2004年11月2日
The latest round of Middle East peace talks are abruptly halted when a key delegate is killed. With the peace process derailed MI5 start to investigate a newspaper mogul and renowned Israeli extremist, and a group he's associated with called the November Committee. Can MI5 prevent an assassination attempt on a pro-Palestinian British MP?
第 5 集 Love and Death
播出时间：2004年11月9日
Saturday morning. Danny and Colin practice their firing technique on MI-5s gun range. Zoe and fiance Will are still madly in love. Ruth watches old movies at home whilst longing for real-life romance. A North Sea mission places additional stain on all relationships...
第 6 集 Persephone
播出时间：2004年11月16日
Zoe is tried for manslaughter when an MI-5 operation results in the murder of an undercover police officer.
第 7 集 Outsiders
播出时间：2004年11月23日
While a deadly hacker turns Britain upside down, Danny decides weather to reveal all to Will, MI5 hunts the source down to an Islamic mosque with the help of Mi5's best computer programmers. But things get suspicious when Ruth, close onto the tail of the hacker, goes missing and so does a member of the special team...
第 8 集 Celebrity
播出时间：2004年11月30日
The baby of a celebrity couple is kidnapped and they call in MI-5. Fiona goes in undercover to gather more information about the couple against Adam's wishes.
第 9 集 Frequently Asked Questions
播出时间：2004年12月7日
When known mercenary Robert Morgan is spotted at a top-secret disused Soviet arms dump, he obviously has to be brought in for questioning. Is it all right to blackmail innocent people to get the information you want? Is it acceptable to threaten the lives of a suspect's family?
第 10 集 The Suffering Of Strangers
播出时间：2004年12月14日
It's Fiona's birthday, and she's not going to forget it!While inspecting a possible Islamic terrorist safe house, they are kidnapped. With the threat of his son's , his wife's and Danny's life Adam must choose who won't live to see another day, Fiona or Danny? The prime minister's life is in danger, will mi5 give into the kidnappers demands - but then to everybody's surprise....Danny makes the ultimate sacrifice.
