[1] The USS Defiant, commanded by Captain Benjamin Sisko, is dispatched to bring supplies to Starfleet soldiers on planet AR-558, the site of a captured Dominion communications relay.
The remaining soldiers are badly in need of relief: they have not been rotated off-duty for over five months, although regulations insist that infantry be rested every 90 days.
When the Dominion's soldiers, the Jem'Hadar, arrive to attempt to retake the installation, Sisko takes command of the garrison, ordering the Defiant away to safety.
Dax assists the garrison's engineer, Kellin, in working out a way to make the "Houdinis" visible, so that they can be moved out of the camp and used to halt attacking Jem'Hadar.
In the aftermath of the battle, the Defiant returns, accompanied by the USS Veracruz, which evacuates the wounded and replaces them with fresh troops.
[2] "The Siege of AR-558" featured Bill Mumy in a guest role as Kellin; the actor had previously appeared in the science fiction genre television series Lost in Space and Babylon 5.
But Deep Space Nine producer Ira Steven Behr offered him a human role in this episode, which Mumy accepted after reading the script for an hour.