Gwyneth Shepherd, a 16-year-old student, feels dizzy for the first time during lunch at her school in London. Not long after, she unintentionally jumps through time while leaving the house. At first, Gwen is doubtful about her jump in time, since her cousin Charlotte Montrose has always been destined to have inherited the time travel gene that is passed down through the females in their family. Charlotte had been prepared for that duty her whole life, and resents Gwyneth for messing up her life plans. Gwen experiences two more uncontrolled jumps through time, during the third of which she witnesses herself, or a double of hers, kissing a boy she has never met at a ball in the 1700s. After her third jump, Gwen’s best friend Lesley convinces her to tell her mother, who had apparently counterfeited Gwen’s birth documents to protect her from the Guardians. The Lodge is skeptical of the circumstances, but decide to watch Gwen to confirm that she has in fact inherited the time travel gene. Gwen travels through time once more and is finally acknowledged as the final time traveler, the twelfth, whose symbolic gem is the Ruby. Gwen’s blood is fed to the chronograph, the time travel machine that contains secrets of its own, so that she can use it travel through time smoothly and avoid uncontrolled jumps. The chronograph is also the second one made, the first one having been stolen by Lucy, the daughter of Gwyneth's Uncle Harry, and Paul, Falk de Villiers younger brother. Gwyneth is assigned the arrogant and disapproving Gideon de Villiers to watch her. Soon after this, Gwyneth is scheduled to meet the founder of the lodge, the powerful Count Saint-Germain. For reasons unexplained to Gwen, her mother is strictly against the meeting. Despite this, Gwen travels to meet the Count, hoping she might find some answers. However, Gwen is only left with more questions, and is also suspicious of the Count, who is believed to possess telepathy. After the meeting, the stagecoach of their carriage is instructed by someone unknown to take the two to a park, where they are promptly attacked by three men. Gideon and Gwen ward them off, then travel back to their present time. The next day, Gwen is called back to the lodge, where she is surprised to find that she is needed in order to talk to someone in the past, her great-great grandmother, and the eighth time traveler, Margaret Tilney, in order for her blood to be read in the chronograph, since Gideon had made two attempts to gather Margaret's blood, but both times, she had refused. The two travel back in time where Margaret is expecting them, despite the exact date that was set in the chronograph to travel back in time being kept secret. Lucy and Paul make their appearance, urging Gwyneth to trust them, and to make sure that all twelve time traveler's blood not be read into the chronograph, for fear that the big event that will happen that may cause more destruction than good. Gideon threatens Lucy with a gun, and makes her escort him and Gwyneth out the house, and as the two are running away, she tells Gwen to look up The Green Rider. The two make their escape to a nearby church, inside a confessional booth, where Gideon, unexpectedly, kisses Gwen.