British survivors of January 2013's terrorist attack on a gas plant in Algeria tell their dramatic and harrowing stories. Thirty nine people died and dozens of foreign workers were taken hostage after al Qaeda terrorists stormed the sprawling facility in the Sahara desert and the Algerian army responded with overwhelming force. For the first time survivors tell the inside story of their miraculous escape playing cat and mouse with their captors, being forced to wear a necklace of explosives and coming under fire from Algerian army helicopter gunships. BBC2's award winning This World strand asks why it was seemingly so easy for the terrorists to enter the plant and why the Algerians reacted in the way they did.