A mysterious collection of circumstances bring all the main characters to a particular warehouse in San Francisco, where some mysterious figures (Architects) are making a deal with some Triad officials. Mayhem ensues, and the warehouse burns to the ground.
Hungry after their fight at the warehouse, the group heads to a local restaurant, the Noodle Pagoda, for a meal and a conversation. Unfortunately, they arrive right before a local gang tries to shake down the owner, and ...mayhem ensues. The entire gang gets killed...as does a random family of tourists.
The first season had three primary arcs. First, the "San Francisco arc"; this was eight episodes long if you don't count the pilots. These episodes served mainly to get things started, and tended to stay close to home, including excursions through the gates in Stately Wan Manor.
Second, the "American arc"; this was the first time continuity of plot became dominant, with essentially the entire arc revolving around the search for the Indian map of feng shui sites; ten episodes long.
Third,the "globe-trotting arc"; this mainly dealt with the consequences and loose threads left over from the previous arc. Eight episodes long.
This season had two arcs. First, the "China arc"; this arc was marked by the evolution of the characters from a ragtag bunch without goals to a potent fighting team with strong goals, even if it took a while for them to decide on ends and means. The highlight of this season may be the four-part episode where they defeat an entire army. 13 episodes long.
Second, the "Ascended arc"; the final arc in the first series, it was marked by escalation. The characters got more deliberate about their goals, and their enemies got more desperate to stop them. The season culminated in a special broadcast movie designed to allow for a fresh start in season 6, but the desire for a fresh start resulted instead in an entirely new series: Feng Shui! The Next Generation. 13 to 15 episodes long, depending on how you count the movie.
After FS:TNG failed, the producers went back to the original well to do the second series of Feng Shui. A couple of the characters from FS:TNG were kept, leading to questions of whether FS:TNG was in continuity or not; they were eventually revealed to be alternate versions of the FS:TNG characters. The characters wandered around the world that had resulted from their actions and decided to do something about it. Culminated in a two-hour season finale, which was broken up into two parts for reruns. 26 or 27 episodes, depending on how you count the movie.
Having defeated one of the primary threats in the post-Shattering world, the group moved on. The current season.