“Change of Heart” is episode sixteen of season six of Star Trek: Deep Space Nine.
Worf and O’Brien are watching Dax playing tongo at Quark’s. Worf is convinced that Dax is going to win – even though he has no idea how the game is played. O’Brien is less convinced, because Quark has won 206 straight games in a row. It turns out that O’Brien is right – even though Dax did well, Quark did better.
The story continues to focus on Worf and Dax, until Major Kira comms them and asks both to come to Sisko’s office. It seems that Starfleet Intelligence has been dealing with an operative, an operative who has now asked for someone to receive a transmission from them in the Badlands. The Defiant is away (which is why Major Kira is running things) as are most of the runabouts. Dax and Worf are going to take the Shenandoah into the Badlands.
On the way to the Badlands, Worf and Dax are looking for somewhere to spend their honeymoon. Worf is looking at some, rather energetic, ideas for honeymoons. Dax wants something more enjoyable – Worf assumes she means Risa, but Dax has picked another vacation spot.
The spy, a Cardassian, says that he has valuable information; he knows how many Founders are in the Alpha Quadrant and what they are doing. In exchange, he wants out, as he thinks the Dominion is getting very suspicious. He isn’t willing to wait for Dax and Worf to communicate this to Starfleet. Instead, he wants them to come in person to another planet and get him out. They will have to land the Shenandoah and pick the spy up in person in three days. At one point, the Shenandoah flies though a typically unrealistic asteroid field. They also have to go on a two day trek through a jungle that sounds rather like one of Worf’s honeymoon plans.
Back on DS9, O’Brien is looking into playing tongo, because he wants to break Quark’s winning streak. So he starts practising with Bashir. Unfortunately, it seems that Miles is no good at tongo. O’Brien wants to beat Quark for the challenge – and because Keiko has been away for six months. So he suggests that Julian beat Quark instead.