Key Out of Time is the fourth and final book about Ross Murdock. The first book in the series is The Time Traders, in which a teen-age Ross is recruited to the Time Service and enthusiastically begins learning to deal with the past and with aliens. The second book, Galactic Derelict, sends Ross and Gordon in search of a spaceship wrecked on Earth in prehistoric times. The Defiant Agents focuses on Travis Fox, who is sent with a team of other Native American volunteers to occupy a planet before the Soviets can claim it. The first two books exhibit great enthusiasm about the unbounded possibilities of space and time travel. In the third book, however, humans are shown as incapable of handling important secrets from the past; this pessimism carries over into Key Out of Time, in which Ross is marooned in the past because he...