Deadly City: He opened his eyes, but this made no difference. The blackness remained. The pain in his head brightened and he reached up and found the big lump they'd evidently put on his head for good measure—a margin of safety.

Secrets of the Martians: Few colonists had seen a Martian, so why worry about them causing trouble? Yet Spencer had been killed—and Rex Tate trapped by the—

Traitor's Choice: Kendall had a difficult decision to make; if he defied the aliens Clare faced a horrible death; if he complied a whole planet must die!

(Summaries by Paul W. Fairman)