The Burn’s true origin comes to light in a heartbreaking moment (Photo: Star Trek Discovery Season 3/CBS Television Studios in association with Secret Hideout, Roddenberry Entertainment, and Living Dead Guy Productions)

Star Trek Discovery Season 3 Ending Explained: We Finally Know What Caused The Burn

Su'Kal's painful past leads to a universe-altering revelation.

The Season 3 finale reveals that Su’Kal, as a frightened child, is responsible for causing The Burn. With Saru’s encouragement, Su’Kal faces the painful memory of his mother’s death when he was a young child. After losing her, he was left all alone on the KSF Khi’eth, a ship on a dilithium planet within a remote nebula.

Su’Kal’s mother had made him promise not to shut off the holo until the Federation arrived, never knowing that help wouldn’t come for another 125 years. Su’Kal is a polyploid, which means his genetics were altered by his environment.

A lost child’s sorrow changes the course of history (Photo: Star Trek Discovery Season 3/CBS Television Studios in association with Secret Hideout, Roddenberry Entertainment, and Living Dead Guy Productions)

Since he was born on a dilithium-rich planet, he developed a deep connection with the element. When he lost his mother, his sonic scream sent a subspace shockwave that caused The Burn. Now that he is no longer on the nebula, it seems unlikely that such a tragic event will occur again.

“I’d like to help repair what is broken, if I can,” Su’Kal tells Saru, indicating that this may not be the last time we see him.

The Bridge Crew Saves the Day

In this episode, the Bridge Crew of the Discovery once again takes centre stage as they carry out a daring mission to sabotage the ship’s nacelle, forcing it out of warp. This act allows the Federation and its allies to catch up with the ship.

They do so under the belief that it could lead to their deaths, as Osyraa has cut off life support to the lower decks, and they only have one oxygen tank between them. It’s Joann, who is surprisingly equipped with impressive lung capacity, who manages to complete the mission.

With the help of one of the DOT-23 droids, she takes the oxygen tank, leaving her friends behind to die, as per their wishes. “I love you all,” she says to them, which seems like a perfect last statement.

However, once Michael regains control of the ship, she restores life support to the lower decks before her crew members perish.

Are Keyla and Joann Together?

The close bond between Keyla and Joann continues to raise questions about whether they share a romantic connection. In the season finale, after the nacelle explosion, they exchange a brief but meaningful exchange: “You’re alive.” “So are you.” Soon after, we see them embracing.

Although I believe that platonic relationships are just as important as romantic ones, I can’t help but wonder if there is something more between them. I truly hope we get to see more of their dynamic in Season 4.

Michael Kills Osyraa

While forcing the ship out of warp was only part of the solution, regaining control of the Discovery is another challenge that falls to Michael. With some help from Book and a thrilling sequence in the turbolift, she makes her way to the ship’s data core.

She manages to fend off Osyraa’s goons, but Osyraa gets the upper hand and pushes Michael into the data core. Just when it seems like Michael might not make it, shots from within the core take out Osyraa once and for all. Michael emerges, standing tall, and says to Osyraa, “Unlike you, I never quit.”

While this line may not have been the most fitting in the moment, the imagery of Michael merging with the Discovery to defeat Osyraa is powerful and full of thematic meaning. It reflects how the ship has truly become a character in its own right, growing alongside its crew throughout the season.

Book Can Pilot the Spore Drive

In one of the biggest revelations of the season, it’s revealed that Book, due to his ability to communicate empathically with plants and animals, can now pilot the spore drive. The Discovery crew takes a significant risk when they jettison the warp core while aboard Osyraa’s ship, Viridian.

In the end, Book successfully figures out how to make the jump, but it’s a close call. This development holds major implications for the future. Although Book has expressed interest in joining Starfleet, his new ability to pilot the spore drive could make him a key asset not just to the Discovery, but to the Federation as a whole.

Yeah, Stamets is Still Pissed at Michael

One unresolved issue that lingers at the end of Season 3 is Stamets’ lingering anger at Michael for forcibly removing him from the Discovery during the season’s penultimate episode.

While Michael’s actions were arguably the right decision—removing Stamets ensured that Osyraa couldn’t force him to use the spore drive—the resentment is understandable. By physically ejecting Stamets from the ship, Michael denied him the chance to choose whether he wanted to stay and help save his crew.

But that’s the harsh reality when you volunteer to be the only spore drive pilot in the universe.

Gray Gets a Corporeal Form, Then Loses It Again

One of the more heartwarming moments in the Season 3 finale is when Gray gains a corporeal form while inside the holo-program, giving others besides Adira the chance to see and interact with him. Hugh, in particular, takes the opportunity to give Gray a big hug.

The holo program gives Gray a Vulcan form, while Adira’s form is Xahean. But for Gray, the most important thing is that he can finally be seen. As the holo is dismantled, Gray tells Adira and Hugh that he no longer wants to go back to his previous invisible state. “It’s not enough,” he says. “I’m stuck. Tal’s stuck.”

Hugh promises that they will find a way to make sure Gray is seen, but the episode ends with Gray returning to being invisible to all but Adira.

Burnham Becomes Captain of the Discovery

The Discovery ship, known for its frequent leadership changes, ends the season with a new captain, Michael Burnham, who has replaced Saru. Saru has taken a leave of absence to help Su’Kal settle into his life on Kaminar, but it’s unclear how long he’ll be gone.

Discovery’s crew rises to the challenge in the face of danger (Photo: Star Trek Discovery Season 3/CBS Television Studios in association with Secret Hideout, Roddenberry Entertainment, and Living Dead Guy Productions)

When Michael suggests waiting for Saru’s return to make a permanent decision, Admiral Vance disagrees, with Saru’s blessing. The question now is whether Michael will be the permanent captain, and the show leaves room for that decision to be made as they begin planning for Season 4.

The Federation is Back on Its Feet

The season finale ends on a high note, not just for the Discovery but for the entire Federation. With Osyraa dead, the cause of The Burn discovered, and the Discovery equipped with two spore drive pilots, things are looking up for the future.

Michael’s closing voiceover reveals that the Discovery is now in a position to deliver dilithium to the Federation’s worlds that had been cut off since The Burn. This new resource will help them reconnect with the Federation.

As a result, Season 4 is poised to explore even more themes of discovery and diplomacy than before. We also learn that Trill has decided to rejoin the Federation, and the Ni’Var have reopened communication with the Federation.

The Ni’Var’s willingness to respond to Michael’s call for help shows their potential to once again become part of the Federation.

What Does the Closing Quote Mean?

The Season 3 finale of Star Trek: Discovery ends with a tribute to Gene Roddenberry and his vision for the franchise, including the following quote: “In a very real sense, we are all aliens on a strange planet. We spend most of our lives reaching out and trying to communicate.

If during our whole lifetime, we could reach out and communicate with just two people, we are indeed very fortunate.” This closing quote is not only a tribute to Roddenberry but also serves as a timely reminder of the importance of connection.

As showrunner Michelle Paradise shared with Comicbook.com, this quote was chosen because it resonated with the team. “Gene Roddenberry, we’re only here because of what he did and because of the show that he created. It felt appropriate to have something from him, a quote from him at the end of our season.”