“In the Pale Moonlight” is episode nineteen of season six of Star Trek: Deep Space Nine.
The episode opens with Sisko narrating his personal log in his quarters. He can’t even remember the date; it’s only been two weeks since something happened, and he feels a need to explain what it was and why he did it. And that what happened went wrong. So the episode is after the events in question.
Sisko had been posting the official list of the Starfleet personnel injured, missing or killed during the war, something he does every Friday. One of the ships, captained by someone Dax knew, disappeared near the Romulan Neutral Zone. It seems that the Jem’Hadar have a habit of crossing the Neutral Zone and ambushing Starfleet ships. The Romulans, as they have a treaty of non-aggression and friendship with the Dominion, turn a blind eye to violations of their territory.
Dr. Bashir says that they need to bring the Romulans into the war on the side of the Federation/Klingon alliance. Dax says that the Romulans have no reason to enter the war, as they can just sit back and watch their rivals wear each other out. So Sisko decided at that point that the Romulans needed bringing into the war. Sisko says that it’s in the Romulans’ best interest to join the war. Only how to convince the Romulan Empire of that? Currently, they are getting benefits for no risk. The Dominion might stab the Romulans in the back at some point, but there is no proof – as Dax, playing devil’s advocate states. So Sisko needs proof. An invasion plan by the Dominion would do just that, but such a plan would be held in a heavily guarded facility on Cardassia Prime. Which would be a problem, but Sisko knows someone who might be able to do it. Garak.
Garak is not too enthused about going on such a suicide mission, but Sisko states that there is no need for Garak to go personally. Surely, as a former member of the Obsidian Order, he still has some contacts and markers to call in. Which Garak does, but this will use them all up. Sisko is willing to do whatever it takes to bring the Romulan Empire into the war. Which it sounds like he later regretted. The road to hell and all that.
Before the plan goes ahead, news is received that the Dominion has invaded – and captured – Betazed. Which puts a number of important Federation planets at risk, and a new ally would be really useful right now. Garak had spoken to a number of people on Cardassia Prime who were willing to help. Within a day, all of them were dead. Garak is not willing to give up. So he suggests that they manufacture the evidence – evidence that seems totally genuine – of a Dominion plot against the Romulan Empire themselves. Which Sisko ends up agreeing with. At which point events gradually start spiralling out of control.