Although producer and showrunner Bryan Fuller has been holding any and all details about Star Trek: Discovery close to his vest, he has not been shy about dropping references and sly hints concerning what we can expect from the new show when it premieres early next year. For example, we know that the show will be set a decade before the events of the original series and that it will deal with an event that will be familiar to Star Trek fans that has never been depicted on screen before. But anything beyond that? Go ahead and consult your crystal ball, because Fuller isn’t confirming or denying anything, it seems.

That brings us to the latest Bryan Fuller tidbit: to commemorate Star Trek‘s 50th anniversary, he revealed that a famous episode of the original series is a “touchstone” for Star Trek: Discovery. What is the Balance Of Terror Star Trek Discovery connection? Let’s take a look.

In a tweet, Bryan Fuller said that “Balance of Terror,” a first season of the original series, is “…a touchstone for the Star Trek: Discovery story arc.” Of course, he said it with more hashtags and in all-caps because he is obviously VERY, VERY EXCITED TO BE MAKING A NEW STAR TREK SHOW AND CAN YOU BLAME HIM?

A FAVORITE TOS EPISODE "BALANCE OF TERROR" IS A TOUCHSTONE FOR THE #STARTREKDISCOVERY STORY ARC #STARTREK50 #LLAP50 pic.twitter.com/3UqKS46Tnu — Bryan Fuller (@BryanFuller) September 9, 2016

“Balance of Terror” is one of the most famous episodes of the original Star Trek series and a fan-favoite, having recently been voted the eighth best episode of all the various Trek shows by fans. The episode is a thrilling and action-packed hour, but it also establishes the groundwork for an important cornerstone of the overall Star Trek mythology.

If you haven’t seen “Balance of Terror,” you should get thee to the digital store of your choice to download it and give it a watch. But here’s what you need to know: the episode finds Captain Kirk and the crew of the Enterprise battling a Romulan Warbird that has been attacking Federation outposts on the edge of the “Neutral Zone,” the border that was established between Federation and Romulan space following a devastating war between the two of them a century earlier. In fact, “Balance of Terror” features the first time a member of Starfleet has seen a Romulan since their conflict (and their physical resemblance to Vulcans is very much a plot point). Ultimately, the episode is a terrific slice of Cold War-inspired tension, with both sides hunting each other through space in what is essentially a sci-fi submarine battle. Without “Balance of Terror,” the more widely famous submarine-inspired showdown of Star Trek II: The Wrath of Khan may not exist.

So here’s the question: when Fuller says “Balance of Terror” is a touchstone, is he referring to the actual events of the episode or the overall tone of the episode? If it’s the latter, he could be suggesting that Star Trek: Discovery‘s heavily serialized first season could be an extended game of cat-and-mouse, with the titular ship squaring off against a powerful enemy where a single wrong move could mean death for everyone involved. If it’s the former…well, who knows? Since Discovery takes place a decade before the original series, that means no one has seen a Romulan in one hundred years, which means that it’s unlikely for the series to involve Romulans in a significant capacity. You just know this news is making the hardcore fans, the ones who obsess over the franchise timeline, pull their hair out of their heads.

Star Trek: Discovery will premiere in January 2017. We will eventually learn more about it.