When two 24th-century chrononauts travel back in time, they inadvertently disrupt the voyage of the Hinden-burg-causing it to land successfully. Now, lost in a parallel universe, their mistake will be felt by every single human being.
"The master of science fiction intrigue." (The Washington Post)
The story is a bit convoluted until near the end when all is explained. It keeps you guessing and allows you to guess what is going on, but the ending is very interesting. The storyline is believable.