As one of a handful of UK police officers trained in SAS deep-cover surveillance, David Corbett infiltrates the toughest communities living among junkies, prostitutes, murderers and firearm dealers, in order to gather evidence that would lead to dozens of convictions.His rapport with hardened criminals was forged during his youth on the mean streets of Glasgow, where he ran with the gangs, joyriding and stealing. But when his friends began disappearing...