Hippocratic Oath

Returning from a mission in the Gamma Quadrant, Bashir and O'Brien respond to what they believe is a ship in trouble on a remote planet. Instead, a plasma field causes them to crash-land on the surface, where they become prisoners of Jem'Hadar soldiers. They intend to kill the pair, but when they learn Bashir is a doctor, the leader, Goran'Agar, orders the men taken to a holding area.

Goran'Agar soon takes Bashir to a makeshift lab where he must carry out scientific research — or die. Goran'Agar explains that he has been mysteriously cured of his addiction to Ketracel-white, the drug the Dominion genetically-engineered the Jem'Hadar to require for survival. Goran'Agar wants Bashir to find the cure so that his soldiers can escape the Dominion's tyranny — a task he must complete before their drug supply runs out in five days. Bashir requests O'Brien's assistance, and they work on a device to help them escape, pretending it is actually part of Bashir's research. But a soldier named Arak'Taral becomes suspicious and activates the device, injuring Meso'Clan, another Jem'Hadar. Arak'Taral grabs O'Brien and threatens to kill him, but Goran'Agar orders him spared.

Having decided to stop living by the Dominion's brutal rules, Goran'Agar also spares Meso'Clan, who would have been otherwise killed by the uninjured soldiers. Bashir is excited by this show of compassion, and later tells O'Brien that he believes they should help Goran'Agar. If they can free the Jem'Hadar from their Dominion leash, he reasons, this could reduce the Dominion threat to the Alpha Quadrant. O'Brien doesn't share Bashir's sentiments — the Jem'Hadar are bred to kill. He flatly refuses to help, so the doctor pulls rank and orders him. Instead, O'Brien engineers his own escape into the planet's dense jungle.

Goran'Agar orders Arak'Taral to bring back O'Brien alive. But when the order is refused, the Jem'Hadar commander realizes his men will no longer obey him. Bashir suggests that Goran'Agar find O'Brien first, promising in return to stay and continue working. While O'Brien is being hunted, Bashir makes progress and soon is onto a discovery that could lead to a cure. At that moment, O'Brien walks in, ready to help Bashir escape, but is shocked when the doctor refuses to go.

Certain the Jem'Hadar will kill Bashir even if he finds the cure, O'Brien destroys the experiment. Goran'Agar sees the damage and sadly allows them to leave, saying he will kill his soldiers in combat rather than subject them to the pain of dying without the drug. Bashir and O'Brien return to the station, each disagreeing with the actions of the other, but at least coming to an understanding.