Quark: You think the whole galaxy is plotting around you, don’t you? Paranoia must run in your species, Odo. Maybe that’s why no one has ever seen a changeling. They’re all hiding!
A Mindaran ship arrives on DS9 w/ twin brothers, Ah-Kel and Ro-Kel (Randy Ogelsby), known as smugglers. Another mysterious alien, Croden (Cliff De Young), has been spending time in Quark’s bar. He comes from the Gamma Quadrant, so is one of a kind on DS9. There are reports of he and Quark (Armin Shimerman) having long convos. Odo (Rene Auberjonois) disguises himself and catches Quark negotiating w/ the Mindarans about an artifact (probably stolen). Odo can’t prevent Croden from killing Ro-Kel while trying to steal the artifact. Ah-Kel vows revenge, as twins of his species are like two halves of one being.
[Croden has killed Ah-Kel’s brother in self defense]
Ah-Kel: My only purpose in life from here on… is to see him dead!
Croden, who is roguish and talkative, tells Odo that he has seen shape-shifters before (he uses the term “Changeling”- a first for DS9). He claims they once lived on his home planet, but were driven out. He saw them on another planet a few years ago and can take Odo there. Croden opens a locket containing a shape-shifting fluid; Dr. Bashir (Alexander Siddig) declares this is partly organic (living) matter! Sisko (Avery Brooks) and Dax (Terry Farrell) go through the wormhole to inform Croden’s people that he has been arrested. They want no contact w/ outsiders and demand his return. Sisko agrees; Odo is tasked to fly Croden back.
This is a strong ep which was inspired by a Western. New viewers, as well as fans who are re-watching, will enjoy this story. It turns out that the prisoner is not what we assumed. We may wonder if he deserves death, as his planet has no trials. The security chief is faced w/ a conflict between his duty and his desire to learn more about his people. We get to see Odo unsettled (very rare); he and Croden have to rely on each other to survive. In the end, we realize that (unlike Federation officers), Odo has his own sense of justice!
Odo: [to the stone changeling] Home… Where is it? Someday we’ll know… cousin.
In the shot in which Rom places the drink bottle onto the tray, we see that there are five glasses instead of four. The camera focuses on the fifth glass in homage to Hitchcock’s Notorious. According to writer Robert Hewitt Wolfe, Odo’s line: “I’m a security chief, not a combat pilot” is a tribute to Dr. McCoy’s running line in TOS: “I’m a doctor, not a….” The exterior visuals of the vortex are re-used shots of from Star Trek II: The Wrath of Khan, w/ color slightly changed and flipped upside-down.
…gives us more insight into him [Odo], especially his efficiency and integrity as a law enforcement officer, while at the same time giving us a peek past his cold exterior to see his inner loneliness and vulnerability.
 The resolution to this story is highly satisfactory and tells us something important about Odo. As we’ve come to expect, Auberjonois and Shimerman give stellar performances.
-Excerpts from IMDB reviews