Plot summary
Dax and Worf are sent to meet with Lasaran, a Cardassian double-agent who wishes to defect to the Federation. Lasaran has valuable military intelligence, but will share no information until he is extracted by Dax and Worf. In three days, he plans to walk into the jungle on the planet Soukara; seeing no alternative, they agree to rendezvous with him there.
Once Dax and Worf land their runabout on Soukara, they have two days to reach the rendezvous point. They must trek through 20 kilometers of dense jungle, and will have to evade the Dominion's surveillance and patrols. They hike the entire day, finally stopping to make camp after night falls. Despite the difficulty of the journey, it is almost like a honeymoon for the newlyweds, who enjoy talking and joking together. However, they soon realize they are in the path of a patrol of Jem'Hadar, the Dominion's soldiers. They manage to kill all three Jem'Hadar, but Dax is shot with a disruptor that leaves an anti-coagulant in her wound — meaning the bleeding cannot be stopped.
With the help of painkillers and regular plasma transfusions, they continue their trek, but Dax's injuries impede their progress, and eventually she loses the ability to walk. Since they cannot abandon their mission, Dax and Worf agree Worf must keep going, leaving Dax behind to die. The newlyweds share a kiss goodbye, and Worf heads off into the jungle. But as he gets farther away, Worf realizes he cannot complete the mission. Instead, he rushes back to the now-unconscious Dax, reaching her just in time to save her life.
Back on Deep Space Nine, he learns she will recover, but their mission is a complete loss: Lasaran has been killed. Captain Sisko informs Worf that, as captain, he must issue a formal reprimand, lessening the possibility of Worf ever getting his own command, and prohibit any further missions with Worf and Dax as a team—but as a man and a husband, he would have done the same thing.
In a side plot, Miles O'Brien tries to coach Julian Bashir to win a game of Tongo, a Ferengi gambling game, and break Quark 's winning streak; Quark wins by reminding Bashir of his former infatuation with Dax, leaving him too distracted and glum to focus on the game.
Credits
Adapted from Wikipedia contributors, Change of Heart (Star Trek: Deep Space Nine). Paragraphs and formatting adjusted; illustrations, reference markers, block quotations and non-story material omitted.