A visitor from the Gamma Quadrant attempts to steal a valuable item that Quark is buying from a pair of twin Miradorn, but Odo stops him. The remaining Miradorn vows to kill the man who shot his brother. Once the visitor, who introduces himself as Croden, is in a holding cell, he makes several comments to Odo regarding Changelings. This piques Odo's interest, as he has never encountered another shapeshifter.
Croden claims to have met one before. Crodon's motives are suspect as he never divulges anything outright, but he claims there were once shape shifters on his homeworld. According to Croden, they were persecuted and driven off the planet; however, he may know of a place where they still exist. Odo is not fooled by the fact that Croden conveniently cannot give directions but can find his way to this place himself. However, Croden gives Odo a necklace with a stone that changes shape.
Sisko and Dax meanwhile try to contact Croden's homeworld about what to do with him. Apparently highly xenophobic, one of their leaders demands Croden's return. Sisko tells the man that a runabout will return with Croden aboard in the next 52 hours.
Back on the station, Croden claims that he happened upon an uncharted colony of Changelings in a nebula he calls the Vortex and that he knows his way back to it. Sisko has other plans and gives Odo the assignment of bringing Crodon back to his homeworld. Odo takes Croden in a runabout and manages to slip by the Miradorn's ship without being detected, but the Miradorn, still bent on killing Croden, forces Quark to tell him where Croden went.
During the trip to Croden's homeworld, he drops hints and is persistent about the Vortex, knowing Odo wants to find his people. The ship suddenly shakes; the Miradorn has fired on it while Odo was distracted with Crodon's story. The Miradorn hails Odo and orders him to surrender his prisoner, and when he refuses, the Miradorn ship attacks the runabout. As Odo says in trying to evade the Miradorn, "I'm a security officer, not a combat pilot!" Crodon says he can maneuver the ship through the Vortex and that the gases might hide it.
In trying to avoid the Miradorn, Croden is forced to land the runabout in order to keep the other ship from finding it. Once on the asteroid on which Croden spoke of before, Odo demands to know if any of the stories were true. Croden admits that on his homeworld people tell stories about Changelings but he has never met one and he does not know where the stone came from. However, his daughter is in a stasis chamber on the asteroid. As they leave the asteroid with the Miradorn in pursuit, Odo tricks them in into firing while inside a highly volatile gas cloud which completely destroys the Miradorn vessel. Ultimately, Croden decides to answer for his crime on his homeworld and asks Odo to care for his daughter but Odo finds a Vulcan ship that agrees to take Croden and his daughter back to Vulcan with it. Croden gives Odo his necklace containing the Changeling stone as a sign of thanks for saving him and his daughter.
During the episode Odo exclaims "I'm a security officer, not a combat pilot!" as a nod in the direction of Dr. Leonard "Bones" McCoy from Star Trek The Original Series (TOS).