Time travel. Imagine if it were possible right now. Where would you go? Would you travel to ancient Egypt to find out how they built the pyramids? Would you visit the bridge of a certain ocean liner on the night of April 14, 1912, and warn the captain to slow down, because there's an iceberg ahead? Or would you go somewhere else, somewhen else?
Rosina and the Travel Agency takes place in the twenty-fourth century, when time travel is as routine as traveling from one city to another is today. When the scientific principle of successful time travel was discovered in the twenty-second century, the excitement was tremendous. It was thought that time travel would be used for the betterment of humanity. Travelers could go back in time and prevent wars, avert disasters and just generally fix things!
Except they couldn't. Time travel turned out to have certain inviolable rules, making most of the goals its creators had for it impossible to carry out.
By the time Rosina and her fellow teenage travel agents arrive on the scene, time travel is used primarily for entertainment purposes, to ferry rich, finicky tourists to the past, where they invariably complain about how the past is not nearly as nice as they'd expected it to be.
Rosina gets fed up, and when she gets an opportunity to play truant from the Agency, she takes it, with unforeseen results.