​The reluctant assassin is Riley, a Victorian boy who is suddenly plucked from his own time and whisked into the twenty-first century, accused of murder and on the run. Riley has been pulled into the FBI's covert W.A.R.P. operation (Witness Anonymous Relocation Program). He and young FBI Agent Chevie Savano are forced to flee terrifying assassin-for-hire Albert Garrick, who pursues Riley through time and will not stop until he has hunted him down. Barely staying one step ahead, Riley and Chevie must stay alive and stop Garrick returning to his own time with knowledge and power that could change the world forever.

Young FBI agent Chevie Savano arrives back in modern-day London after a time-trip to the Victorian age, to find the present very different from the one she left. Europe is being run by a Facsist movement known as the Boxites, who control their territory through intimidation and terror. Chevie's memories come back to her in fragments, and just as she is learning about the WARP program from Professor Charles Smart, inventor of the time machine, he is killed by secret service police. Now they are after Chevie, too, but she escapes—into the past. She finds Riley, who is being pursued by futuristic soldiers, and saves him. Working together again, it is up to Chevie and Riley to find the enigmatic Colonel Clayton Box, who is intent on escalating his power, and stop him before he can launch missiles at the capitals of Europe.

Riley, an orphan boy living in Victorian London, has achieved his dream of becoming a renowned magician, the Great Savano. He owes much of his success to Chevie, a seventeen-year-old FBI agent who traveled from the future in a time pod and helped him defeat his murderous master, Albert Garrick. But it is difficult for Riley to enjoy his new life, for he has always believed in his heart of hearts that Garrick will someday, somehow, return. Chevie has assured Riley that Garrick was sucked into a temporal wormhole, never to emerge. The full nature of the wormhole has never been understood, however, and just as a human body will reject an unsuitable transplant, the wormhole eventually spits Garrick out. By the time Garrick makes it back to Victorian London, he has been planning his revenge on Riley for centuries. But even the best-laid plans can go awry, as the three discover when they are tossed once more into the wormhole and spill out in a Puritan village. Featuring remarkable heroes, an epic villain, and monstrous mutations, The Forever Man is another high-octane adventure from the impressive imagination behind the internationally best-selling Artemis Fowl series.