The book was a lot better - I didn't see the movie, but in the book the writer returns from fighting the Japanese with his arm blown off from storming an island. He is in love with a Japanes woman in his village (who he used to run around with as a kid), but her family feels it is shameful for her to be with a white man. His anger boils over when she asks him about his arm and he says "The Japs did it".
He ends up proving the innocence of her Japanese husband who is accused of murdering a rival fisherman - the husband is also a US war vet who fought the Germans, and is horrified of the killings he had to do.
I shouldn't be surprised that they ruined it for the movie.