Sites offering "Full Downloads" of vintage or niche media are often hubs for "bundled" software, which can include spyware, ransomware, or browser hijackers [1].
You can read O. Henry’s "Behind the Green Door" for free on sites like Project Gutenberg or American Literature . Behind the Green Door - Full Download -
If you are looking for the content, there are safer ways to access it: Sites offering "Full Downloads" of vintage or niche