This episode was directed by Michael Dorn (who also played the role of Worf in the show) and written by Rene Echevarria.
In episodes preceding this one, Gul Dukat, the Cardassian who governed Bajor under the occupation, disguised himself as a Bajoran and won the favor of the ambitious Bajoran spiritual leader Kai Winn, seducing her to the path of the Prophets' evil counterparts, the Pah-wraiths; the Cardassian leader Damar has launched a rebellion against Dominion rule; and the Changeling Founders of the Dominion have developed a mysterious illness with no known cure.
This episode advances those plot lines, as Dr. Julian Bashir discovers that DS9's security chief Odo, a rogue Changeling, has been infected with the Founders' disease; Starfleet sends DS9's Bajoran second-in-command, Kira Nerys, to assist the Cardassian resistance; and Winn turns Dukat away.
Anticipating the Cardassians' objections to being advised by a Bajoran former terrorist, Sisko has Kira given a Starfleet commission to lend her more authority.
Starfleet bureaucrats stonewall his request, claiming that the records are classified and questioning Bashir's loyalty for trying to cure a disease that primarily threatens the Federation's enemies.
[5] In 2016, The Washington Post called the Dominion war story arc, of which this episode is a part, possibly the "richest narrative" of the Star Trek universe.