Foundation Season 3 Episode 4 recap: Demerzel’s secret role in the Star Bridge incident is finally revealed

Foundation Season 3 Episode 4 aired on July 30, 2025, and revealed several major shifts across Trantor, Ignis, and New Terminus. Demerzel admitted to orchestrating the Star Bridge bombing to ensure Hari’s survival. Pritcher returned from Kalgan with disturbing insight into the Mule’s mind-control abilities.

Gaal warned Dawn of the Empire’s refusal to act, prompting his escape from Trantor. On New Terminus, Quent forced Dusk to reveal the Prime Radiant. Day murdered Mavon after stealing Demerzel’s Mycogen tech. Meanwhile, Dawn chose to join Gaal, abandoning his Empire role, while the Mule’s influence continued to spread.

Demerzel confirms to Vorellis that she orchestrated the bombing of the Star Bridge on Trantor.

In Foundation Season 3 Episode 4, the show reveals an extended part of Demerzel’s earlier confession where she admits to planning the attack that killed millions. She arranged for extremists from Anacreon and Thespis to detonate explosives on the Star Bridge.

The goal was to save Hari Seldon by forcing the Empire to embrace psychohistory. Without the explosion, Hari would have been executed. Demerzel did not share what she promised the attackers in return, but believed the long-term survival of the Empire justified her decision.

In Foundation Season 3 Episode 4, Vorellis questions this logic and challenges Demerzel to face the scale of her actions. The conversation causes visible discomfort in Demerzel, suggesting internal conflict or possible programming limits. She becomes unsettled when Vorellis discusses a future where Demerzel could exist without serving the Empire.

This reaction implies she may be unable to process alternatives that break from her assigned duty. Although she succeeded in keeping Hari alive and shaping the Foundation, the cost was massive, and now others know what she did. This is the first time anyone within the show has directly tied Demerzel to the event in plain terms.

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Foundation Season 3 Episode 4: Dawn abandons Trantor after meeting Gaal again

In Foundation Season 3 Episode 4, Dawn leaves the Empire after a face-to-face meeting with Gaal changes his path. Gaal appears in person on Trantor to speak with Dawn about the rising threat posed by the Mule. She warns that the Enclosure plan won’t work, and the Empire is underestimating the danger.

Dawn believes he can stop the Mule once he becomes Day, but Gaal explains that if it hasn’t happened already, it likely never will. She urges him to leave Trantor and join her. Dawn demands more information before agreeing and only changes his mind after she shows him her Mentalic powers.

She explains that Kalgan’s threat isn’t isolated and that people like the Mule are targeting others like her. Dawn follows her into Trantor’s tunnels to avoid detection. He learns that there is an entire group with abilities like Gaal’s who are preparing for what’s next.

He decides to leave the city with her. This is the first time Dawn willingly separates himself from the Dynasty without consulting Day or Dusk. Whether he’s defecting or acting on intel remains to be seen, but his absence now leaves the Empire without its future ruler. No one on Trantor is yet aware of his departure.

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Foundation Season 3 Episode 4: Day kills Mavon and escapes with forbidden Mycogen Tech

In Foundation Season 3 Episode 4, Day murders Mavon after stealing equipment linked to Demerzel’s origin. Day tricks Demerzel into revealing a key piece of Mycogen tech used in her maintenance. While she’s distracted, he steals one of the tools and brings it to Mavon. Their agreement involves Mavon helping him escape the palace in exchange for nanites that could save Mavon’s daughter. Mavon leads Day to the boundary of the Mycogen district and prepares to part ways.

As part of their deal, Day extracts the nanites and gives them to Mavon, only to shoot him in the head moments later. He injects the nanites into Mavon’s body, dumps him into a river, and leaves undetected. Demerzel later realizes she has been tracking Mavon’s corpse. Guards confirm the nanites are no longer functioning. This sequence confirms that Day has gone fully off-grid.

He now possesses the stolen Mycogen device and is no longer being monitored by the Empire’s internal security. With Demerzel unaware of his location and Day’s motives unclear, the path ahead for both the palace and the Mycogen sector becomes unstable. There is no communication between Day and the other Cleons at this point in the story.

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Foundation Season 3 Episode 4: The Prime Radiant’s location forces Dusk to cooperate with Quent

In Foundation Season 3 Episode 4, Quent exposes Dusk’s secret, pushing him to finally activate the Prime Radiant. On New Terminus, Ebling informs Quent that Hari plans to emerge from the Vault during an upcoming eclipse. But it’s Quent’s reaction to another detail that shifts the balance.

She learns that the Empire still has a copy of the Prime Radiant and that Dusk has been hiding this from everyone. She confronts him and offers a trade: allow the Foundation to question Bayta, Toran, and Magnifico, and in return, share the Radiant’s projections. Dusk refuses, so Quent forces his hand by making his secret public. With no other choice, he orders Demerzel to surrender the device.

They activate it together in private, and the Radiant begins showing them its predictions. It’s a rare moment of cooperation between the two powers, but neither mentions the part of the projection that warns of the Empire’s destruction in four months. For now, the device is online, and both sides are looking at the same future for the first time in the series.

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