An extremist ideology is sweeping across Europe. Fundamentalist terrorist groups are operating in London. They want to end the British way of life and a minority are prepared to bomb and kill to get what they want.

But the year is 1892: Victorian England, where the government is fighting a war on terror against many of its own citizens.

Over 100 years later, Britain is home to another community which some claim is in deep conflict with its fundamental values.

The Enemy Within explores the discontent which fuelled radical sentiment in the 19th century and the anger that fuels it again today.

It tells the story of a largely forgotten period of English history - an Anarchist insurgency that took place in Victorian London - and examines the parallels that can be drawn with the modern-day war on terror.

A cast of non-professional actors, young British Muslims, speak the words of the 19th-century Anarchists involved with the terror campaign. Their performances are intercut with interviews in which they explain how they feel about being a Muslim in Britain today.

The programme uses surveillance-style camera techniques to evoke an atmosphere of tension and paranoia as it examines the feelings of oppression, persecution and anger that can lead to extremism.