Andre Norton 
Defiant Agents 

A battle for survival begins and ends in the human mind in the thrilling novel from the Time Traders series. The latest gambit by the Western powers to outmaneuver the Russians was Operation Cochise—which launched Travis Fox and his crew on a ship bound for the planet Topaz. At least that’s what Fox thinks . . .   All he knows for sure is that something went wrong and they crash landed. Everything else is a fog of warped memories. When they come across a band of Russians who have also had their memories obliterated, Fox begins to suspect they are all pawns in a much larger game. And his speculations are right.   Someone is manipulating them. Observing them. And if Fox and his newfound allies cannot find a way to break free from their mental bonds, their captors may never be stopped.The Defiant Agents is the third book in the Time Traders Series, but you may enjoy reading the series in any order.