The reference to "Season 18" likely stems from a misunderstanding of episode numbering.

Revisiting the dark, gritty, and transformative first season of Arrow is a must for any comic book fan, and watching it in the 720p format allows the stunt choreography and dark atmosphere to shine.

This is the most dangerous part of the search. The request for "single free" indicates a desire to download the entire series as one large file at no cost. This leads us directly to the world of piracy, which comes with significant risks.