This episode aired March 3, 2019.
As Team Fireball is held at blaster-point, Commander Pyre charges them with conspiring against the First Order. Yeager demands he explain his false accusations, and Pyre says that the Fireball was reported as having been used by Resistance spies trespassing in the FO-controlled Sector Epsilon 51-3. Tam protests that this is all a mistake, but Kaz and Yeager don't deny anything, Kaz only saying that "It's complicated." As Pyre orders the troopers to take Team Fireball away, Yeager spots Bucket, who was in the back of the shop and unnoticed by the stormtroopers. He covertly signals the droid, who pushes away a crate and fills the room with smoke. In the subsequent chaos, Yeager, Kaz, Neeku and CB-23 are able to barricade themselves inside Yeager's office, but Bucket is shot and falls into the sea, and Tam, believing that this is all just a misunderstanding, doesn't run and is caught by stormtroopers. Pyre orders Tam brought up to the tower holding cells for questioning, insinuating that her friends deliberately left her behind to take the fall.
In the tower, Torra tells her father she doesn't think he's doing enough against the First Order. Captain Doza points out that he's doing what he can, but it gets harder every day. Commander Pyre enters and asks if he's interrupting anything, which Doza denies. Pyre informs the Dozas that Yeager and his employees have been unmasked as Resistance spies, but only one of them was captured: Tam. Doza, noticing an approaching shuttle, demands Pyre tell him who's coming, and he responds that the new arrival is Agent Tierny of the First Order Security Bureau, who will no doubt want to speak to the First Order's captive.
Yeager leads Kaz, Neeku and CB-23 through his private hangar to the maintenance shafts. Inside, Neeku asks why the stormtroopers are after them, since they're definitely not spies. Kaz tells Neeku the truth, that he is a spy, but the Literal-Minded Nikto responds that this is a very bad time to be telling jokes. Yeager tells them this isn't the time as they have to get a move on. Eventually, the trio's loudness gets them overheard by stormtroopers, who enter the passages to chase them. They are eventually surrounded, but are then fortuitously rescued by a trap door opening beneath them, which deposits them with waiting Chelidae maintenance workers. Kel and Eila, approaching, reveal that they overheard Kaz and company due to how loud they were, hence the rescue.
At the tower's landing pad, Captain Doza and Commander Pyre meet Agent Tierny as she gets off her shuttle. After they reach Doza's office, Tam is brought in, and Tierny orders her binders removed. The agent is friendly to Tam, and takes her out of the office so they can talk. Tam is surprised when they wind up in a section of the Aces Lounge, and Tierny orders a service droid to prepare refreshments. As drinks are served, Tam tells the agent that she doesn't know anything about the Resistance at all. When Tierny mentions Commander Poe Dameron, Tam says she doesn't know him personally, but she knows that Kaz and Yeager are friends with a pilot by that name. Tierny asks her about Kaz, and Tam says he's just a poor kid from Coruscant. The agent corrects Tam, showing her a datapad with Kaz's military service record and revealing that Kazuda Xiono is actually a member of one of Hosnian Prime's richest families, a pilot in the New Republic Navy who was recruited into the Resistance. Tam studies the datapad in shock.
In engineering, Kel and Eila show Kaz, Yeager, Neeku and CB-23 to a room where two Chelidae have just finished fixing up Bucket, who they retrieved in their fishing nets. Everyone, especially Yeager, is overjoyed to see the droid is all right. Discussing their next step, Kaz points out that there are two things they have to do: rescue Tam and contact the Resistance. However, they can't think of a way to break past the First Order's jamming signal, especially as the jammer is on top of Doza Tower. After Yeager points this out, Kaz has an idea: they sink the entire platform except for the very top of the tower, placing the transmitter just above the water level and allowing a team to swim from the lower levels up to the tower easily. Yeager thinks the plan is crazy, but Neeku finds he's excited about it. However, they don't have many other options. Kaz sends CB-23 up to the tower to tell Captain Doza about the plan as he'll need to seal the bulkheads to prevent the platform from flooding entirely. She gets into the tower by ambushing a First Order ball droid delivering a tray of food. When CB gets to Doza and Torra, the captain is initially confused as he didn't order anything, but Torra recognizes her as Kaz's new droid. Doza also thinks the idea of sinking the Colossus is insane. When CB gets back to engineering, she plays Kaz a message from Doza: he gives Kaz permission to carry out the plan, as Torra adds that she finds the idea exciting.
Kaz, Yeager, Neeku and the Chelidae shut down the Colossus' turbines, causing a loss of power that will make the platform sink. In the Aces Lounge, Tierny and Tam are shaken by the sudden jolt, and the agent leaves to find out what's going on, with Tam guarded by a couple stormtroopers. When Tierny and Pyre meet Doza in his office, they realize that the platform is sinking, which Doza speculates to have been caused by a reactor malfunction. Pyre gives Doza permission to seal all the doors and bulkheads, and Doza, addressing the entire platform, informs the residents that This Is Not a Drill and to get to the designated safe areas as the platform is sinking. Pyre and Tierny quietly discuss the suspiciously convenient timing of the incident. The marketplace's blast doors are closed just in time, as almost all of the Colossus slips beneath the waves. When the Colossus has settled, Kaz and Yeager don breathing masks and, with CB-23, slip out of the bottom of the Colossus before swimming to Doza Tower, the humans towed by the droid. They climb onto the side of the platform, where the transmitter is located, and after a few seconds, Yeager locates and pulls out the chip regulating the jamming signal. In Doza's office, Pyre and Tierny realize that the jamming signal is down, for which Doza suggests the cause may be water damage. Tierny, looking out the window, notes that the transmitter is above water, and Pyre leaves to deal with the situation.
Kaz and CB-23 quickly send a message to the Resistance. A response comes quickly, but as CB-23 is downloading it, Pyre and a few stormtroopers arrive, causing Kaz and Yeager to have to take cover. Yeager fires at the troopers, briefly locking out Pyre's troopers by shooting the door lock. However, it doesn't take them long to open the door and rejoin the fight. After CB confirms she has the entire message, Yeager tells Kaz that, although he wasn't the best spy, he'd be proud to fight alongside him anytime before pushing him into the water. As CB follows, Yeager is arrested by the stormtroopers. Meanwhile, onboard the sail barge Galleon, out on the open ocean, Valik informs Kragan that they've intercepted a coded transmission, which he orders her to decode. Synara pushes her way to the front of the crowd as the pirate reveals the contents: a message from Kazuda Xiono to the Resistance.
When Kaz and CB-23 return to engineering, they tell the others about Yeager's capture, as now he needs to be rescued too. Kaz asks CB if she got the whole message, and she confirms it before playing a recording of General Leia Organa. Leia tells Kaz that unfortunately the Resistance has their hands full, and she has no ships she can send to reinforce them. She has, however, sent Kaz the coordinates for the Resistance's next base, and tells him to join them if he can make it off Castilon. She finishes off by telling him that he's not alone, as there are people all across the galaxy who are fighting for freedom. "May the Force be with you."
Kel and Eila are horrified that the Resistance won't be coming, while Neeku, having finally realized that Kaz was not joking about being a spy, wants to know why he didn't tell him earlier. Kaz points out, though, that like General Organa said, they're not alone. All of them will have to be the Resistance now, and they're going to rescue Tam and Yeager and take back the Colossus.
- Affably Evil: Agent Tierny plays a "Good Cop" to butter up Tam, letting her out of her binders and being kind and welcoming. Tam is too Genre Blind to realize she might have an ulterior motive, especially given her feelings of betrayal after she learns Kaz's real background.
- Bittersweet Ending: Kaz and the others manage to contact the Resistance, but Leia tells them that the Resistance has their hands full and also tells Kaz that he can join up with the rest of them if he is able to escape from Castilon. Of course, Yeager and Tam have both been captured. Kaz and the others resolve to take back the Colossus on their own.
- Broken Pedestal: Tam loses faith in Kaz and Yeager when she learns that they've been lying to her to cover up their involvement with the Resistance as well as using the Fireball in the name of the Resistance, since this almost gets her arrested by association, as well as almost causing her to lose her only chance to get back into racing.
- The Bus Came Back: Kragan Gorr's Warbird gang appears again, and they've been wandering the skies of Castilon out of reach of the station.
- Call-Back: In "The Core Problem", while escaping the Colossus, Poe expressed concern that the Fireball's colourful paintjob would be spotted by patrolling TIE fighters. Now, the ship's distinctive appearance gets Team Fireball arrested by the First Order, when they realize it's the ship spotted in Sector Epsilon 51-3.
- Continuity Nod:
- Tam's assumption that Kaz is a poor kid from Coruscant seems to have stemmed from what he once told her about allegedly working in a factory there.
- Neeku once again hand-gags himself when Yeager tells him to be quiet.
- Just like in the final episodes of Rebels Season 1, the heroes hijack an Imperial communication device to send a message, the mentor lets himself get arrested to let the others escape, the heroes' boss can't/won't send help, leaving our heroes on their own to save the day, and their message is also seen by an unexpected party that ends up becoming helpful later.
- Crazy Enough to Work: The general reaction to Kaz's plan to sink the Colossus so he, Yeager and CB-23 can more easily reach the First Order's jammer.
- Cuffs Off, Rub Wrists: Tam, after Tierny orders her binders taken off.
- Delivery Guy Infiltration: CB-23 ambushes a First Order roller to get the food it was attempting to deliver to make it look like she's delivering food to Captain Doza. He wasn't the intended recipient, but she had to in order to convince him to sink the station.
- Department of Redundancy Department: After Yeager says that Kaz's plan is "so crazy it might just work", Neeku responds that it's "so crazy it might be crazy".
- Disney Death: During the escape from the repair shop, Bucket is shot by a stormtrooper and falls into the ocean, horrifying Yeager. When they get to engineering, Kel and Eila reveal that the Chelidae snagged him in one of their fishing nets and have just finished repairing him.
- Entertainingly Wrong: Tam, angry that Kaz and Yeager have lied to her the entire season about their allegiance to the Resistance, decides to join the First Order, convinced that once she proves her innocence, the First Order will leave her alone and see her as an ally. As we already know, the First Order couldn't care less about her beyond being a tool, and Tam is playing a risky game that puts both her and everyone else in danger.
- FaceHeel Turn: Tam decides to join the First Order to prove her innocence after learning that Kaz and Yeager have been lying to her and get her arrested by association.
- Fall Guy: When Tam is captured, Pyre insinuates that her friends deliberately abandoned her to take the fall.
- Hand Gag: Neeku claps a hand over his mouth when Yeager suggests that he and Kaz be more quiet while sneaking around the subfloor maintenance corridors.
- Heroic Sacrifice: Yeager lets himself get caught to secure Kaz and CB-23's escape from Doza Tower.
- Internal Reveal: Kaz is publicly outed as a Resistance agent to his friends.
- Is This a Joke?: When Kaz admits to Neeku that he's a spy, Neeku tells him that this is a very bad time to be joking. It isn't until he sees the message from Leia at the end that he realizes Kaz was never joking.
- Mugged for Disguise: CB-23, sent to the tower to tell Captain Doza about Kaz's plan, lures a First Order ball droid carrying a tray of food off before taking it out of commission and swiping the tray, allowing her to pose as the messenger and get in the tower. Since most people don't pay very much attention to droids, it works like a charm despite her much more colourful paintjob.
- No One Gets Left Behind: Although General Leia cannot send assistance, she gives Kaz the option to escape to their next base and regroup there. Kaz has no intention of doing so just yet, because he refuses to leave everyone behind and decides he will help them expel the First Order.
- One-Word Title: "Descent".
- Reality Ensues:
- Kaz, Neeku, and Yeager get into a long, emotionally-charged conversation while sneaking around in the maintenance tunnels. Because it's emotionally-charged, it gets really loud and the stormtroopers easily find them (and lucky for Team Fireball, so do Kel, Eila, and the Chelidae).
- Kaz flying the Fireball in combat against the First Order in "The Core Problem" is what outed him as a Resistance agent, owing to the distinctive paint scheme and the fact that he was trespassing in a restricted sector alongside Poe's X-Wing.
- Shaped Like Itself: After Yeager says that Kaz's plan is "So crazy it might just work," Neeku retorts that it's "So crazy it might be crazy!"
- Synchronous Episodes: This episode overlaps with The Force Awakens.
- This Is Not a Drill: Captain Doza says this while ordering Colossus residents to report to secure areas because the station is sinking.
- Trap Door: The Chelidae rescue Kaz, Yeager, Neeku and CB-23 when they're cornered by stormtroopers in the maintenance tunnels this way.
- You Are Not Alone: Leia tells Kaz this in her message, pointing out that there are people fighting oppression across the galaxy. Kaz then tells the others this, stating that they are the Resistance now, after learning that there won't be any outside help coming.