One World is the explosive tale of James Gilmour, a British SAS soldier, and his personal fight with terrorism on mainland Britain. During the assault of a hi-jacked aircraft, Gilmour befriends an eight year old girl whose mother has been shot. After the assault, Gilmour snatches the girl from Social workers he believes are not working in her best interests. His actions bring down the fury of his superiors and Gilmour finds himself being thrown out of the Regiment. Returning from a shopping trip, the back doors of a transit van burst open and guns are brandished. During the ensuing scuffles an SAS mate is shot dead and Gilmour is taken hostage along with the girl and a female Sergeant. With the American President's State visit to Britain imminent, Whitehall finds itself greatly alarmed over the shooting and kidnapping of SAS soldiers, and tasks Peter Ellis, an unconventional freelance operative, to investigate. From a dying man in a disused quarry on the outskirts of Belfast, Ellis learns of an IRA terrorist cell operating on the British mainland. Meanwhile, Gilmour is imprisoned in a cellar. He kills one of his captors and escapes with the Sergeant, with whom he is developing a powerful relationship, but of the girl there is no sign and they are forced to abandon her. Gilmour and Ellis then team up and return to the farmhouse where they uncover a clue that leads the investigation to the Highlands of Scotland. As part of a small patrol, Gilmour is parachuted into the Highlands to observe a fishing lodge in a remote glen. The patrol witnesses the murder of a young woman and recklessly assaults the lodge. During the confrontation, a car bomb in a Range Rover detonates killing two of the patrol members and seriously injuring a third. When Gilmour regains consciousness, he searches the lodge and finds the girl, only to be taken captive again, this time by al Qaeda terrorists. Gilmour escapes, but again has no option but to leave the girl, and becomes embroiled in a desperate race to rescue her, involving car chases, helicopters and motorway shoot outs. Ellis meantime, finds himself drawn into the ruthless world of a secret Religious Order that will stop at nothing to accomplish its goal.