Murray Leinster
Nobody ever saw the message-torp. It wasn't to be expected. It came in on a course that extended backward to somewhere near the Rift—where there used to be Huks—and for a very, very long way it had traveled as only message-torps do travel. It hopped half a light-year in overdrive, and came back to normality long enough for its photocells to inspect the star-filled universe all about. Then it hopped another half light-year, and so on.
...Murder Madness! Seven Secret Service men had completely disappeared. Another had been found a screaming, homicidal maniac, whose fingers writhed like snakes. So Bell, of the secret "Trade," plunges into South America after The Master—the mighty, unknown octopus of power whose diabolical poison threatens a continent!