After falling through his computer screen, Zack travels back in time to a school in 999 A.D. where the students believe the world will end in the new millennium.
The Time Warp Trio find themselves in the middle of an adventure in prehistoric times, where cave art is a form of graffiti and "rock" music takes on a whole new meaning.
On a visit to England, Susan finds herself mysteriously transported back to the time of World War II, where she meets a Viennese Jewish refugee and a prejudiced young boy who help her understand and appreciate her background.
Time travelers Joe, Fred, and Samantha inspire General George Washington during the winter of 1776 to carry out a surprise attack on Hessian troops in Trenton, New Jersey, that will eventually change the course of the Revolutionary War.
Unhappy about her family's upcoming move, twelve-year-old Emma wishes for a friend and is suddenly confronted with a spoiled, lonely girl transported from the 1850s by a mysterious doll.
When he finds an ancient, egg-shaped object with which he travels back and forth in time, eleven-year-old Tycho grapples with several terrible futures he sees for himself and his family.