“The Maquis: Part 1” is episode twenty of season two of Star Trek: Deep Space Nine.
A Cardassian freighter is departing DS9, but before it leaves, a man in a Starfleet uniform attaches something to it. Shortly after it undocks, the freighter explodes, killing all aboard.
There are worries that this will cause problems with the peace treaty between the Federation and the Cardassians. Gul Dukat arrives surreptitiously on the station and asks Sisko to accompany him into the demilitarised zone, where there are some Federation colonies that refused to leave following the treaty.
Whilst they are in the DMZ, they witness two Cardassian ships attacking a Federation freighter, before they are themselves destroyed by another Federation ship. The situation in the DMZ is rapidly spinning out of control, and back on DS9, a Vulcan is arranging a large purchase of weapons. It seems the DMZ will soon become the MZ.
The Maquis were originally French resistance bands during World War II.
The story continues in “The Maquis: Part 2”.