The Stranger Club

"Guard this letter as you would your life!" With these words ringing in his ears, Biff Brewster boards the Brazil-bound plane to join his father on a safari to the headwaters of the Amazon River--a safari that, to Biff's amazement, becomes a deadly contest for fabulous riches.

The "Stranger Club" is a very exclusive society which does not welcome strangers; you understand the meaning of the name when you see the motto of the club close to the ceiling in the great hall:

TRUTH IS STRANGER THAN FICTION.

The Complete Series by Laurance Manning as originally published in Wonder Stories pulp magazine.