The new, grittier era of Star Trek television owes its tone and storytelling style to one series and one episode in particular: Star Trek: Deep Space Nine and its most celebrated/controversial installment: “In the Pale Moonlight.” Its conflict-centric premise and the conventional rules of Star Trek it dared to break has had a lasting impact through the writers' rooms of every series that followed. The dark tone of Star Trek: Picard and Star Trek: Discovery, and their future where humans are in conflict with one another, violence is sometimes the answer, and every character is a darker shade of gray, began with DS9 and found its footing in season 6, episode 19.

Over the course of the episode's 45-minute runtime, its hero, Captain Benjamin Sisko has sacrificed much of what he holds dear: his honor, his integrity, even his sense of morality. Facing a losing war against the Dominion, and seeing only one chance for victory, he "lied, cheated, bribed men to cover the crimes of other men," and became an accessory to murder (not to mention roughing up a certain station tailor). By the end of the episode, when the truths are laid bare, an emboldened Sisko speaks directly to the audience, affirming that despite all the viewer has learned and all he has learned about himself, “I can live with it.” All of this was shocking for Star Trek at the time, as it represented such a stark departure, but it is a decision which now feels very at home in a universe where Picard breaks interstellar law and Michael Burnham is just as comfortable solving conflicts with her fists.

Related: DS9 Did Star Trek Into Darkness' Story First (& Way Better)

Star Trek: Deep Space Nine was the first series to come about following creator Gene Roddenberry's passing. As such it reflects a much different version of the future from that of his original vision. Roddenberry's edict for the show was for it to represent an evolved form of humanity. Gone was the desire for personal wealth or material gain, replaced with a thirst for knowledge and exploration. Gone also, according to his vision, was conflict among humans, even on the personal level. Members of Starfleet could present varying viewpoints, but they were never to be shown in direct conflict with one another. They should, according to Roddenberry, always be shown as paragons of human virtue. It was DS9's “In the Pale Moonlight” that broke this tradition more than any other episode, proving how this kind of conflict could not only happen, but provide rich drama and character development, and it continues to inform Star Trek today.

Star Trek: In The Pale Moonlight

The graymmorality on display in these new series would never have gotten past Roddenberry's red pen, but it was a necessary direction to take after years of the show's writers expressing frustration with Roddenberry’s “no conflict” rule. So much of Western storytelling revolves around the inherent conflict between people, that many writers never felt on solid ground in the peaceful, understanding world of the 24th Century. It took the Dominion War arc, and a character as dramatic as Benjamin Sisko, to make them realize they could tell a traditional Star Trek story in a non-traditional way.

The success of the episode, which has long been hailed by fans and critics alike as one of DS9's best, and the new opportunities for narrative exploration it opened up, are readily apparent in Star Trek: Picard and Star Trek: Discovery. With scenes as shocking as Jean-Luc and an Admiral cursing at one another over their disparate ideologies, or with such morally questionable characters as Captain Lorca and Mirror-Georgiou interpreting the rules of the Federation to suit their own needs, Star Trek has entered a new frontier, pioneered by Star Trek: Deep Space Nine. Just like "In the Pale Moonlight," the writers are able to show that Star Trek can still be about championing a more hopeful future, but it can also ask some challenging questions. Perhaps  none bigger than: “What price is humanity willing to pay for a brighter tomorrow?” While different in approach, it is a question very much at the heart of what Gene Roddenberry would’ve wanted to see.

Next: The Complete Star Trek Timeline Explained