Synopsis by Hans J. Wollstein
In 1918, a member of his own squadron shot down an ace flyer known as the Eagle in the mistaken belief that he was the enemy. Fourteen years later, a threatening note demanding satisfaction arrives at the Evans Aero Corp., whose board constitutes the surviving members of the Eagle's World War I squadron. One of the board members, Green (Lloyd Whitlock), discovers that the man they used to call the Eagle, Nathan Gregory (Edward Hearn), is still very much alive but wheelchair bound and the operator of a carnival. When Gregory, who has been blaming the Evans Aero Corp. for stealing an invaluable invention of his, suddenly disappears, young stunt pilot Craig McCoy (John Wayne) accuses the board of kidnapping. The meeting, however, is interrupted by a mysterious skywriting message showing the name "Clark" slashed by a horizontal line. The lights go out and a disconcerting voice intones: "the Eagle has struck!" When the light comes back on, Clark (Edmund Burns) is found murdered. Even Craig believes Nathan Gregory to be the killer, but the carnival operator's daughter, Jean (Dorothy Gulliver), swears to his innocence. A man resembling Gregory takes off in McCoy's airplane and attempts to kill both Craig and Jean.