Picking up a newspaper or turning on the television news it is difficult today to avoid headline stories about the latest activities of IS. It was just over a year ago on extremist websites that a short audio recording was released by IS in which its leader, Abu Bakr al-Baghdadi, declared a new caliphate. Today whether one accepts or rejects that such a caliphate exists, there is no getting away from the fact that IS now controls a swathe of territory across Iraq and Syria of well over 125,000 square miles, inhabited by some six million people. Many of these people of course would wish to be anywhere other than at the mercy of IS diktats.

As the latest dangerous manifestation of the global jihadist movement set in train by Osama bin Laden and Ayman al Zawahiri towards the end of the 1990s, it would be hard to refute the fact that IS has gone some considerable way to seeing through its three-stage evolution towards the creation of its caliphate. Along the way its management of savagery certainly has never been in doubt. Countless beheadings, crucifixions, the burning alive or throwing of people from high buildings have all too graphically confirmed this to a world that looks on aghast.

But if savagery represents one significant strand in IS strategy, so too by contrast does its sophisticated use of digital technology in delivering its message to the same horrified world. This is what lies at the narrative core of Atwan’s latest offering on the labyrinthine mechanisms that shape events in the Middle East and Islamic world.

Like Atwan’s other works the research that backs up his discourse is impeccable and authoritative. When marshalled to make a point it is presented with a clipped clarity that reminds the reader of his verbal delivery during broadcast appearances on programmes like the BBC’s Dateline London. This is an author who writes as he speaks, robustly and with a sense of surety about the material at his disposal. This is all the more welcome for the lay reader who understandably is often daunted by the factionalism, acronyms and alphabet soup that frequently accompany accounts of extremist groups in this region. To that end, for example, Atwan drops in very useful ‘mini guides’ along the way, such as a summarised Map of the Syrian Opposition, reminding readers of key groups and players.

Far and away the main thrust of this book and its greatest intrigue, though, lie in its insights into the remarkable and powerful use of digital technology IS have deployed alongside an ideology that embraces medieval barbarism. In an odd way the incongruity of this reminds me of something I encountered some years ago during a visit to Cambodia. There in the country’s capital, Phnom Penh, I visited the Tuol Sleng Genocide Museum which was once a notorious torture and interrogation prison run by the extremist communist Khmer Rouge.

The Khmer Rouge, like IS, was notoriously barbaric in their implementation of ‘Year Zero’, their version of a ‘caliphate’ where people were compelled to accept a culture, traditions and belief systems that, in the case of the Khmer Rouge, eschewed the trappings of modern life, be it cars, refrigerators or the wearing of spectacles. In a bizarre twist to this, many of those who became victims at Tuol Sleng for breaching this diktat were recorded on film by their Khmer Rouge captors who saw no irony in using modern state-of-the-art cameras.

This paradox is also evident in the case of IS as outlined by Atwan’s book. Put simply, the clash between advanced 21st-century technology and the Salafist- jihadist interpretation of Islam espousing the values of life in the 7th century, ceased to be a topic of debate when IS realised the internet’s capacity for spreading or reinforcing their message.

The author makes the case that IS would never have become the force it is or achieved its territorial ambitions without not only ‘managing’ savagery but mastering the internet as well. IS in effect is a ‘brand’, one reinforced by cadres not merely carrying Kalashnikovs. As Atwan says, its ranks are “tech-savvy… with most of the digital caliphate’s business conducted online, from recruitment and propaganda to battlefield strategy and instruction”.

Right now there is no shortage of books looking at the evolution, structure, ideology and threat the Islamic State group poses. While some are clearly the work of thorough research, they seem primarily aimed at the academic market or students of terrorism or security studies. Once again Atwan has written a book that is both accessible to the lay reader while casting new and invaluable insights into a complex group that is shaping the current Middle East and the foreign policies of governments beyond. Any reader who wants to know what makes the Islamic State group tick would do well to start here.

Islamic State – The Digital Caliphate by Abdel Bari Atwan is published by Saqi Books, £16.99. The author will be at the Edinburgh International Book Festival on August 23