Key Out of Time

Time travelers land on a planet that seems like paradise but poses hidden dangers, in this tale by “one of the finest writers in the field of science fiction” (The New York Times).
 
Time Agents Ross Murdock and Gordon Ashe have accompanied a group of settlers to the planet Hawaika, which is populated by descendants of Earth’s Polynesia. But while it seems like a tropical paradise, there are some disturbing signs of previous inhabitants who apparently vanished.
 
Accompanied by Karara—a local girl who can communicate with dolphins—Murdock and Ashe travel to the past to see if the disappearance is connected to the mysterious alien race, the Baldies, who have manipulated Earth’s own history. Unfortunately, a violent storm wrecks their time gate, stranding them in past Hawaika.
 
Murdock and Ashe discover they were right about the Baldies interfering in the past. And unless they can find a way to stop them, the future will pay the price, in this adventure from “an author who has tantalized and enthralled readers” (Saturday Review).

Key Out of Time is the fourth book in the Time Traders Series, but you may enjoy reading the series in any order.