This book is about a cloned scientist who invents the means to time travel and the government who manipulates him into using it for their purposes so they can change certain periods that they feel needs changing. The story takes us from Roswell in 1947, then to 1912 and the sinking of the Titanic, to 1940 and a visit with Anne Frank, to 1963 to visit with JFK, to 1970 to visit the Apollo 13 disaster, then to 1986 for the shuttle Challenger. The time travelers end up back in their present, where they find things have changed.