"Season Four Finale", originally titled "Assassination Run", is the eighth and final episode of the fourth season and thirty-second episode overall of the American satirical superhero television series The Boys. It was written by Jessica Chou & David Reed and directed by Eric Kripke. The episode was released on July 18, 2024, on Amazon Prime Video.

In the episode, the Boys try to stop Victoria Neuman from reaching the White House while also trying to stop the assassination of Robert Singer. Butcher uses his last card to try to defeat Homelander, which is to have Ryan kill his father. The relationship between Homelander and Neuman reaches its most critical point.

While Butcher is recovering at a CIA facility, he has a conversation with Kessler in which Kessler urges him to commit a Supe genocide that would kill Homelander as well, though he rebuffs him before Mallory arrives and calls Ryan. When Ryan arrives there, Mallory, unwillingly to Butcher, tells him all the crimes his father committed and tells him that he has to train him to kill Homelander. When he refuses, Mallory tries to lock him up only for him to shove her into a wall, accidentally killing her. Following Mallory's death, Butcher embraces his dark side as Kessler.

As the votes certifying Robert Singer's electoral victory are being counted, Hughie begins searching for the files incriminating Victoria Neuman only to discover that they have been deleted by the shapeshifting Annie without his knowledge. Without the virus, The Boys, after M.M.'s idea, take Singer to a bunker, and when Hughie discovers that Annie is the shapeshifter, a fight breaks out in which the real Annie ends up killing the shapeshifter. At the same time, Homelander exposes Neuman as Supe on air live and orders the remaining Seven to kill anyone who could incriminate them. One of the targets is Ashley, who injects herself with Compound V and begins to mutate.

After Homelander threatens Zoe, Victoria asks for Hughie's help to break free from Homelander's control. At first, the Boys are hesitant to work with Neuman, but after a speech from Hughie they agree. When they meet at the Boys' temporary base, while the team and Neuman are talking, Butcher arrives and brutally kills Neuman with his new tendril superpowers, taking the dose of the virus.

After Neuman's death, a devastated Homelander is told by Sister Sage that this was the plan and Steven Calhoun, who will be the new president of the United States following Singer's arrest, swears loyalty to him. In a speech, Calhoun declares martial law and Homelander imperiously interrupts him to assure America that the ("official") Supes will take revenge on the "enemies" of the country. All of The Boys are captured except Butcher and Annie, who flies away when she regains her powers. Zoe is captured by Vought troops, who take her to the Red River orphanage.

In a mid-credits scene, Calhoun shows Homelander where Soldier Boy is being held, revealing to Homelander that he is still alive.

The episode features the song "Heart-Shaped Box" by Nirvana.