It's a race against time to rescue a kidnapped scientist in this suspenseful tale by an Edgar Award-winning author.   The world is under threat of destruction. As the politicians hedge their bets with atomic weapons, it seems no one is safe.   The only hope? A brilliant professor who knows how to make nations and people invulnerable to atomic attack. The only problem? Professor Julian Conway has been kidnapped by power-hungry men wishing to use his expertise for themselves.   At British intelligence's top-secret Department Z, Gordon Craigie assigns agent Peter Ross to get the professor back: dead or alive. Complicating the case, though, is the fact that Ross is in love with two beautiful women: one of them the professor's daughter, and the other a possible key to the whole mystery . . .