The series follows John Porter, a former British Special Forces soldier, who is drafted back into service by Section 20, a fictional branch of the Secret Intelligence Service.

The lives of Bodie and Doyle, top agents for Britain's CI5 (Criminal Intelligence 5), and their controller, George Cowley.

The mandate of CI5 was to fight terrorism and similar high-profile crimes. Cowley, a hard ex-MI5 operative, hand-picked each of his men. Bodie is a cynical ex-SAS paratrooper and mercenary whose nature ran to controlled violence, while his partner, Doyle, comes to CI5 from the regular police force, and is more of an open minded liberal. Their relationship is often contentious, but they are the top men in their field, and the ones to whom Cowley always assigned to the toughest cases.

The dramatised account of how the world’s greatest Special Forces unit, the SAS, was formed under extraordinary circumstances in the darkest days of World War Two.

To be trapped behind enemy lines is every soldier’s worst nightmare: a situation they all train for, few experience, and even fewer survive. No Man Left Behind dramatizes the stories of real-life war-heroes whose contribution to the war effort becomes a pure battle for survival against all odds.

Over the past 60 years Britain's Special Air Service regiment has carried out a wide variety of clandestine missions - from deep-penetration raiding to hostage release operations - which have made it respected and feared for its professionalism and daring. The SAS prides itself on doing its work in the shadows, never allowing any publicity and never claiming credit for any of its extraordinary achievements. But, over the years, sufficient information has emerged for a picture of the regiment's exploits to be clear. This series uses interviews with former members of the SAS; detailed and painstaking reconstructions; and cutting edge 3-D graphics to recreate seven great missions which show why the SAS is today regarded as the world's leading special forces unit.