When Billy Reilly vanished, his parents embarked on a desperate search for answers. Was their son's disappearance connected to his mysterious work for the FBI, or was it a personal quest gone wrong? Only when Wall Street Journal reporter Brett Forrest embarks on his own investigation does a picture emerge: of the FBI's exploitation of US citizens through a secretive intelligence program, a young man's lust for adventure within the world's conflicts, and the costs of a rising clash between Moscow and Washington.

Sept. 11th roused Billy Reilly's curiosity for religions, war, and the world and its people beyond his small town near Detroit. Online, Billy taught himself Arabic and Russian. His passions led him into jihadi Internet forums, attracting the interest of the FBI.

An amateur drawn into professional intelligence, Billy became a Confidential Human Source, one of thousands of civilians who assist FBI agents with investigative work, often at great hazard and with little recourse. When Russia stirred rebellion in Ukraine, Billy set out to make his mark.

In Russia, Billy's communications dropped. His parents, frantic, asked the FBI for help but struggled to find answers. Grasping for clues, the Reilly family turned to Brett Forrest. Commencing a quest of his own, Forrest applied years' worth of research, along with decades of extensive experience in Russia, illuminating the inner workings of the national-security machine that enmeshed Billy and his family, picking up the lost son's trail.

A masterwork of reporting, composed like a thriller, blending political manoeuvring and international espionage, Lost Son illustrates one man's coming of age amid new global dangers.