Bluebird is Back

The caper concerns a man who hires nuclear power plant specialists. Seems he's bee selling low-grade intelligence about U.S. nuclear power plants "to the other side."
The cad plans to turn double-agent. But he is terminated with extreme prejudice at a zoo where U.S. agents are waiting for him to meet "the other side." The doom is done with a four-pointed metal weapon, "the death star," a device Hunter recognizes as the trademark of a years-ago foe named "Bluebird," an ace Communist intelligence agent he hates.