‘A Single Source’ tells two stories, which over a few tumultuous months come together to prove inextricably linked. There are the dramatic, world-changing events across North Africa and the Middle East, as protests led by a new generation of tech-savvy youngsters challenge the established order. Then there are two Eritrean brothers, desperate to make their way up from the Horn of Africa across the continent to a better life in Europe. The horrors they endure at the hands of people traffickers and others along the way test their endurance and humanity to its limit. William Carver spots the Arab Spring early, aided by one of the infamous ‘Listeners’ at the BBC monitoring station in Caversham. He and his producer, Patrick, chase the story across North Africa before arriving in Egypt where the battle between the corrupt old order and the new will be both bloody and potentially definitive.