As the combined forces of MI5 and the SAS confront ruthless Islamic fanatics bringing jihad to the UK, two former enemies are reluctantly paired together to combat the threat.

Two deadly but very different terror attacks bring carnage to London on the same day: a suicide bombing in the heart of Soho, and the shooting down of a military aircraft taking part in a ceremonial fly-past. Simultaneously, a previously-unknown Islamic radical calling himself Saladin declares a caliphate in the UK and decrees that all British Muslims should rise up against the infidel state.

The initial terror attacks are followed by sickening atrocities at Jewish schools, and in response to Saladin’s message, disaffected Muslim youths heed the call to arms, establishing Sharia patrols that bring terror to the streets. Others undertake lone-wolf marauding terror attacks. The resultant backlash plays into the hands of a charismatic right-wing politician and threatens to ignite a race war.

The Prime Minister authorises the creation of a multi-agency team, codenamed Artemis, led by an experienced MI5 analyst. This elite new unit brings together top experts from MI5, MI6, GCHQ and the SAS, in a desperate race against time to hunt down the terrorists before they can complete their murderous plan. They’re joined by a former enemy whose knowledge and skills might just be the key to unlocking the entire plot – if he can be trusted.