Plot summary
On board a runabout, Odo and Kira are in pursuit of a member of the terrorist group known as the Maquis. They follow the Maquis vessel to a small moon. Landing, they find the vessel is empty, and split up to search for the pilot. After a short while, Odo returns to find Kira with her foot caught in an expanding crystal mass that Odo is unable to remove.
As Kira is slowly being covered by the crystal, dangerous seismic tremors increase in the surrounding rock; Kira insists that Odo abandon her and flee to safety. He attempts to free her using an ultrasonic generator, and tells her about his past as they wait for the crystal to shatter. When the generator fails to work, and Kira is nearly engulfed in the crystal, Odo confesses his love for Kira. To his surprise, she says she is in love with him too.
Suspicious of Kira's response, Odo points a phaser at her, demanding to know who she really is. Kira and the crystal suddenly morph into a Changeling, one of the Founders of the Dominion (Salome Jens), who reveals that she stole the Maquis ship in order to try to convince Odo to return to the Dominion. She reveals the real Kira's location and transports away. Odo finds Kira and tells her of the Founder, but not of his feelings for her.
Meanwhile, on Deep Space Nine, Nog attempts to convince Commander Sisko to endorse his application to attend Starfleet Academy. Sisko is doubtful and suspects Nog is engaging in some underhanded scheme, especially since Nog's request was accompanied by the customary bribe Ferengi culture expects when making such requests. To test Nog's resolve, he gives him the task of counting the inventory of a cargo bay. Nog completes the task quickly, but Sisko still has doubts.
Sisko tells Nog that he will not give him a recommendation. Nog confesses that he wants to do it so that he does not end up like his father Rom (Max Grodénchik), whose engineering skills are not valued by Ferengi culture. Sisko, stunned by the young Ferengi's upstanding ambitions, agrees to recommend Nog to the academy.
When Nog tells Rom and his uncle Quark (Armin Shimerman) of his intention to join Starfleet, Quark adamantly forbids it; but Rom, in an uncharacteristic act of courage, stands up to his brother and proudly grants his permission for Nog to join Starfleet.
Credits
Adapted from Wikipedia contributors, Heart of Stone (Star Trek: Deep Space Nine). Paragraphs and formatting adjusted; illustrations, reference markers, block quotations and non-story material omitted.