To Serve Man

The Kanamits, a 9-foot tall alien race landed on Earth. Their spokesman announced to the United Nations that they were here to help humanity.

They shared their advance technology. Hunger was eliminated. Energy became cheap. Nuclear weapons were rendered harmless. Deserts were morphed into fertile fields.

Patty, one of the staff of US government cryptographers led by Michael Chambers cracked the title of a Kanamit book the spokesman left behind at the UN.  It's title, she revealed is "To Serve Man." Soon, humans were volunteering for trips to the Kanamit's home planet, which was portrayed as a paradise. Michael Chambers was one of those volunteers,

With the Cold War ended, the code-breaking staff had no real work to do so Patty continued trying to work out the meaning of the text of "To Serve Man."

The day arrived for Chambers's excursion to the Kanamit's planet.  Just as he mounts the spaceship's boarding stairs, his staffer Patty appeared.  She ran towards him in great agitation. While being held back by a Kanamit guard, Patty cried, "Mr Chambers, don't get on that ship! "To Serve Man" ... it's ... it's a cookbook!"

* "To Serve Man" is a science fiction short story written by Damon Knight