During WW II Johnson's plane is shot down and lands in the Pacific. He tries to steer the drifting aircraft to the mythical island of the title, having learned of the place through his grandfather's stories. As a means of surviving, he tells his life story to his injured seamate Cameron
Mitchell. In a flashback we see his youth, his romances with Allyson, then Maxwell, and then Allyson again, and his naval enlistment. We find out that the hopeful Allyson has had her father organize a search party, which eventually locates the nearly dead Johnson. Unluckily for Mitchell, he dies
having had to listen to all Johnson's ponderous reminiscences. Everyth...