The terrorist bombing of a Cardassian supply ship brings to Sisko's and Dukat's attention armed skirmishes between the Federation and Cardassian colonies that reside, respectively, in the other side's areas of the demilitarized zone (due to a recently signed treaty put into effect in TNG's "Journey's End"). The Federation colonists live in constant fear of Cardassian oppression and, at times, blatant assault. As a result, they've taken up arms and formed a terrorist organization called the Maquis—which has led the Cardassian colonies to return hostilities. The terrorism brings one of Sisko's good friends to DS9 to help diffuse the situation: Cal Hudson (Bernie Casey), a Starfleet commander in charge of overseeing the Federation colonies.
"The Maquis" is one of the great examples of complicated political situations that define DS9 as a series. Filled with intriguing plot developments (including weapons smuggling on both sides and the eventual kidnapping of Gul Dukat) and a multitude of characters, "Maquis, Part I" shows all the signs of a slowly percolating situation that will eventually become one of the series' several defining plot lines.
Of particular interest is the extremely interesting role of Gul Dukat in the given situation, as well as his evolving function on the series. Sisko and Dukat are infinitely watchable as reluctant co-investigators, and they have two key scenes in this episode that are marvelous: one in Sisko's quarters, the other in a Runabout. The amount of depth that Dukat's character takes on is welcome and highly commendable, changing his image into something far more subtle and complex than that of a villain. Marc Alaimo's performance is multifaceted—revealing unexpected low-key humor and then turning on a dime to exhibit a menacing persona.
Also of high interest is a great heated argument between Kira and Sisko regarding the Federation colonists' decision to resort to such violent terrorism. Surprisingly, the least effective scenes are the ones between Sisko and Hudson; Bernie Casey's wooden performance misses the mark and somewhat mars some important—and otherwise powerful—dialog scenes of exposition.