Tomorrow's Guardian, by Richard Denning, is the story of a boy named Tom Oakley who discovers that he can "walk" through time. His job as a "Walker" allows him to go back in time and save other Walkers. Unfortunately, a dimension parallel to ours, where the Nazis rule, wants to control Tom's world as well. The story takes the reader from a sinking U-boat to the Great Fire of London, from a Nazi- controled England to a Zulu vs. English battle.
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.