Seasons & episodes

S4 · E1The Special (1) 2005-09-12＋

When a devastating bomb explodes in central London, causing multiple deaths, a terrorist group with a hatred for human life claim responsibility. With their leader facing extradition, the bombers announce that crippling attacks will be launched at ten hour intervals until he is released.

S4 · E2The Special (2) 2005-09-13＋

Zafar and Adam race against the clock to uncover the latest bomb. As a new ultimatum is issued and Tash mysteriously disapears, the team is forced to deal with the possibility of a mole within their own organisation.

S4 · E3Divided They Fall 2005-09-22＋

Far-right political party The British Way is threatening democracy so Adam and Fiona go undercover to infiltrate and destroy its campaign.

S4 · E4Road Trip 2005-09-29＋

Adam infiltrates a truck carrying illegal immigrants across Europe in order to stop a would-be terrorist.

S4 · E5The Book 2005-10-06＋

A neo-conservative group murder an ex-minister to cover up his past and then they hunt down the journalist who is threatening to blow the story and is under MI5 protection.

S4 · E6The Innocent 2005-10-13＋

MI5 suspect a terrorist is planning an attack from his prison cell. Guest stars Jimi Mistry.

S4 · E7Syria 2005-10-20＋

The Syrian foreign minister tries to establish subversive contacts with MI5 at the opening of a cultural centre in London. Fiona is desperate to lead this mission and must confront her Syrian past.

S4 · E8The Russian 2005-10-27＋

An old British traitor is called in to infiltrate a Russian firm suspected of stealing secrets from GCHQ.

S4 · E9The Sting 2005-11-03＋

Harry upsets the CIA by stopping an extradition to the USA.

S4 · E10Diana 2005-11-10＋

A former officer is convinced that MI5 killed Princess Diana and is determined to force the team to prove it.