In Foundation Season 3, Episode 7 titled "Foundation’s End", Mayor Trenton Indbur III of New Terminus meets a grim fate. Indbur is brought before the Mule after he has conquered the city. In a chilling and symbolic moment, Indbur is compelled by the Mule to drown himself in the basin, not by violence but under the influence of the Mule's psychologically devastating power. This act is likely intended as a brutal punishment for Indbur's earlier decision to present Han Pritcher, as a gift to him, who then tries to kill the Mule.
Ultimately, Indbur surrenders, and this not only eliminates a key Foundation leader but also serves as a stark demonstration of the Mule's dominance and cruelty at this late stage in the conflict.
What happens to Indbur in Foundation Season 3 Episode 7? explored in length

As mentioned, in season 3 episode 7, once the Mule invades New Terminus, Indbur initially submits and cooperates with him, bending the knee like most of his subordinates. This sets up the dominance and power of the Mule. First, Indbur tries to bargain by presenting Pritcher as his "gift" to the Mule in the hope of securing a ceasefire. But Pritcher, using his Mentalic powers, has already escaped and even unsuccessfully attempted to assassinate the Mule.
This angered the Mule, who, while saving himself, accidentally loses his man, Randu. This results in him turning against Indbur. The show features a scene where the Mule is forcing Indbur to drown himself, not violently but under the control of his psychic influence. What’s fascinating is Indbur’s expression: instead of rage or terror, he dies smiling, which makes the act feel both surreal and terrifying. It suggests the Mule bent not only Indbur’s actions but his very emotions in those final moments.
Why Indbur's death matters in Foundation?
Indbur has been a prominent ruler of the New Terminus and has ruled it with arrogance and stubbornness. Therefore, to see him fall and that too in a way the Mule did, by stripping his will to survive and reducing him to nothing but a pawn, highlights the scale of the Mule's control. Indbur's death would indeed lead to a political Fallout with New Terminus collapsing and suffering under the Mule's rule. The resistance is now fragmented with Protcher on he run and Toran separated from Bayta.
Furthermore, the imagery of his death, with Indbur smiling, sets up the accurate tone establishing how the Mule's psychic domination destroys autonomy itself, making him one one the most terrifying antagonists in the show.
The Mule frames his backstory as a tale of survival and revenge. He joined the pirates who terrorised his people by choosing the lesser evil over the Foundation. By the end of the episode, he declares how his war against the Foundation is personal, and he is determined to make them suffer.