A 12 year old English boy named Thomas who finds out he is a "walker"--someone who can travel through time--meets a man named Septimus who works for an organization that helps walkers. Septimus gives Tom a small lesson on time traveling, then hands him to an old man they call the Professor to teach Tom more about time traveling, but he must first decide whether he wants this kind of life or if he should instead take the cure the Professor can provide.What makes the situation more intense is that Tom must make the decision before his 13th birthday. Then another man gives Tom the choice of using his powers to help him rule the world. Next Septimus offers Tom the choice of doing whatever he wants to get some quick money. Before Tom can make a decision, the Professor asks for a favor: to rescue some possible "walkers" from the past because Tom is the only one powerful enough to do this. To make matters more difficult, they do not have time to properly train Tom about time traveling and this is where the adventure starts.