Jadzia Dax finally makes plans to undergo her Zhian'tara, in which she has the chance to actually meet her previous hosts by temporarily transferring each one's memories from the symbiont into the minds of each of her closest friends.
The Zhian'tara is the Trill rite of closure. This is a very emotionally intense ceremony which involves the separation of the personalities of the previous hosts from the symbiont into friends of the current host. The relation allows the current host to gain a renewed sense of his/her shared lives. The process takes place with the assistance of a Guardian who telepathically transfers the personalities. Commander Sisko, Major Kira, Dr. Bashir, Odo, Quark, Chief O'Brien, and Leeta have agreed to participate.
Kira accepts Lela Dax, and Jadzia can see that she is the origin of many of Dax's unique characteristics, which she herself now exhibits. O'Brien becomes the shy but friendly Tobin Dax. Leeta receives the personality of Emony Dax, a cheerful and talented gymnast. Quark had been somewhat nervous about taking on the personality of the female Audrid Dax, who tenderly brushes Jadzia's hair as they talk. Bashir is Torias Dax, an adventurous pilot who died young in a shuttle accident. Sisko has to be restrained in a holding cell to receive the personality of Joran Dax, who was a violent murderer. Indeed, when Jadzia comes to meet him and hesitantly lowers the force field between them, he grabs her and tries to strangle her. Verad, from the second season episode "Invasive Procedures," is not among the previous hosts that are separated out, since Verad stole the Dax symbiont and was not joined long enough to be a true host.
Afterwards she expresses some anxiety about the Zhian'tara. She had been a little bit afraid to hear what her previous hosts had to say. The hardest part is still to come: she has not yet met Curzon.
Curzon Dax trained Jadzia when she was a Trill Initiate, studying to prepare herself to apply to the Symbiosis Commission to receive a symbiont. Curzon Dax had flunked her from the program, recommending that she not be approved for a joining. She later reapplied and was accepted, and actually received Curzon's symbiont when he came to the end of his life. Despite having Dax within her, she does not know Curzon's motivations for refusing to approve her to get a symbiont. Furthermore, she is not sure she wants to hear his reasons.
Odo accepts Curzon Dax. When Curzon's memories leave Jadzia and enter Odo, he breaks out in Trill spots and becomes the fun-loving free-spirited "Old Man". When Jadzia tries to talk to him, he evades her questions. Then he says he intends to stay within Odo, and that Odo has agreed to keep him. Jadzia cannot imagine life without the force of Curzon's personality within her, not to mention all of his exciting memories. When Sisko offers to talk to Curzon, who had been his mentor and friend many years ago, Jadzia declines and resolves to face the Old Man herself.
When she demands to hear Curzon's story he finally admits that he flunked Jadzia from the program because he was in love with her. He realized such feelings were inappropriate, and when she reapplied he made sure she was accepted. The symbiont she got was Dax. When Jadzia reassures Curzon he will always be with her, and a part of her, he is satisfied and leaves Odo's body.
Meanwhile, Nog prepares to take the final exam for the crash course which will allow him to later take the Starfleet Academy entrance exam. He is despondent when he finds out that he failed, but Rom discovers that Quark rigged the exam so that Nog would fail. Furious, Rom confronts Quark for interfering in Nog's choice to enter Starfleet. Sisko allows Nog to retake his exam, and this time he passes. At Quark's, after Rom proudly presents his son to the crowd, Nog orders a root beer - something they serve at the Academy.
This episode includes a reference to Fermat's Last Theorem and is considered as a continuity repair for comments made in the Star Trek: The Next Generation episode "The Royale".