Shot on location in the Grand Canyon, the silent western adventure "Sky High" stars Tom Mix as a cowboy investigating the smuggling of Chinese laborers across the Mexican border. Tom also tries to save a damsel in trouble, but soon discovers her father may be the guy behind the smuggling operation. Eva Novak, Sid Jordan co-star. Then, ranch foreman Tom Markham (Mix) was leery when his boss (Frank Beal) gifted his daughter (Kathryn McGuire) a fabulous diamond ring. He'd be proven right when desperadoes try to pull off "The Big Diamond Robbery." 123 min. total. Standard; Soundtrack: music score. Silent with music score.