This is a good Douglas Fairbanks Western. Reportedly, Fairbanks was a Western history aficionado, and he made a few Westerns in between his generally more Eastern-based comedies of the 1910s and before his transition to swashbucklers in the 1920s. This film "The Man from Painted Post" and "Wild and Woolly" (1917) are the only two I've seen, but he also starred in "The Good Bad Man", "The Half-Breed" (both 1916), "Headin' South" (1918) and "The Knickerbocker Buckaroo" (1919). "Wild and Woolly" is more comedy than Western, and it pokes fun at the protagonist's romanticizing of the West; "The Man from Painted Post", however, is a more traditional Western, although it includes some of Doug's characteristic sense of humor and smooth athletic stunts.
Regardless, this is somewhat darker and more dramatic than the other available early films of Fairbanks-and there's more exposition than usual for this star's vehicles and a few unnecessary long explanatory title cards. At the beginning, we're shown a flashback of our protagonist's sister being gunned down and dying in his arms, which explains his contemporary employment as a "detective" for cattle ranchers-that is, a good hired gunman who fights off cattle rustlers, which just seems to be his way of seeking revenge or justice. Yet, Doug plays much of the film with his typical smile and wit, so the result is a somewhat underdeveloped Western dramedy. To complicate matters, there's also a love interest for Doug, as usual. Additionally, 'Bull' Madden, played by Frank Campeau, is appropriately an especially detestable villain, who we see abusing his wife, attempting to force himself onto another woman, and pushing a child around, in addition to drinking, cattle rustling and generally endangering others' lives and well-being.
(Note: I saw a rather poor, dark reduction print/video transfer, which included a few intertitles that were nearly illegible. Consequently, the photography of Wyoming's landscape didn't register very well, although some of the shots, such as the final cloudy horizon view remain lovely.)
