He was ordered to track down a rogue colleague. Now British Intelligence agent Nick Stone and "runner" (and former lover) Sarah Greenwood have become the hunted, racing deeper into a dark, deadly conspiracy that will change the course of world events - and the lives of millions. With seventeen years of active service in the elite SAS force, Andy McNab writes from his own harrowing experiences. Packed with authentic procedural details, as relentless as a fast-burning fuse, Crisis Four is a thriller so gritty and real that you won't know where fact ends and fiction begins.