Walter R. Brooks 
Freddy and the Flying Saucer Plans [EPUB ebook] 

Freddy the pig was lounging in front of the First Animal Bank of which he was president when Uncle Ben raced by with his two sets of flying saucer plans–one true and one false. With spies in full pursuit, Uncle Ben was naturally looking for a safe place to hide the plans–the true ones, of course. As usual, Freddy was ready to help.

And, as always, Freddy digs into his disguises and comes up with a solution to the current problem–this time in the garb of a gypsy fortuneteller.