Synopsis
Flux: 溶剤 Yōzai
Shu has been taken away by GHQ officials, and interrogated as a suspected terrorist. While being held prisoner, Shu starts learning more about Funeral Parlor, a.k.a Undertaker and their plans from GHQ Major Segai. Shu becomes even more indecisive about whose side he should be on than he was earlier; and the fact that Gai refuses to answer any of his questions makes matters even more confusing for him.
While Shu's lost in his own sea of thoughts, Undertaker is already on its way to rescue a known murderer that is also held prisoner by GHQ. Seeing that rescuing him is not part of the plan, who should Shu put his faith and trust in?
Full Plot Summary
Opening theme:
"My Dearest" by Supercell

Shu: Why Yahiro?
As Shu is being arrested by Seiga and GHQ, Inori attempts to break the window by taking out the fire extinguisher, but a female classmate stops her. In a vehicle, Seiga asks Shu about a question in a crossword puzzle while Shu wonders why Yahiro betray him. In a prison cell, an orange suit man bangs his head against the wall. At school, Souta exclaims in astonishment about Shu's arrest; at the same time, Hare and Inori worry about Shu. In the interrogation room, Seiga reveals some images of Shu and Gai talking together, and when he asks Shu about this, Shu refuses to answer him. In another scene, Seiga reports to his superior that there is no doubt that Shu has connections to the Funeral Parlor. His superior reveals a video from Gai who states that they will rescue their comrade no matter what.

Yahiro stay by Jun's side
On the way to an isolation ward, Seiga explains to Shu about how Yahiro is making money as a drug dealer for a purpose. He reveals a clinic area where Yahiro stays by his younger brother, Jun. Jun is in the fourth stage of the apocalyptic viral infection. Shu realizes that Yahiro wanted to help his younger brother; Seiga explains about a violent riot 10 years ago, Lost Christmas, that occurred from the apopocalyptic viral outbreak. He talks about how GHQ find a vaccine to help the sick and how he hates Funeral Parlor for disturbing the peace. Seiga asks Shu why he joins the Funeral Parlor. Shu ask what good will acts that GHQ commit because he witness GHQ killing off people. Seiga justifies that these citizens were unregistered and refused vaccines, and also, the GHQ soldiers are killed by them. Seiga reveals a picture of Kenji Kido (the orange suit man) who is a terrorist bomber and tells Shu that Gai declared to free him by force.
Then, he tells Shu to beware of the people he trust and gives Shu, a transmitter. He instructs Shu to turn it on when Shu talks to Gai. Seiga states that Inori is another girl who brainwashed by Gai and tells Shu that he will ask her for help. In an abandoned warehouse, Inori listens to her sad songs that she sings as she cuddles with Funnel. She asks Funnel why she feels sad. At the prison, Shu meets his lawyer, Mason (Gai). Meanwhile, Tsugumi hacks the system and has the mikes close. Gai tells Shu about their plan to rescue Kido. Yet, Shu refuses to follow their orders and ask them why they fight for. Suddenly, the alarms blared and the bombs explode.
Tsugumi tells Ogumo and the others to fire missiles at the tower; Ayase and the others drive their Enclaves. Gai asks Shu what he will do. Then, Inori calls Shu, but Gai gets mad that she is here. Shu escapes from the room and leaves Gai behind. Gai tells his men that plans are changed; Ayase goes out to help Shu and Inori. When Shu gets attacked, Ayase frees him and asks what Shu did to Inori. She tells Shu that she will beat him if Gai gets hurt. As the GHQ guys push off Kido, Gai shoots a missle at the bridge. Shu spots Kido and takes out his Void. Suddenly, Gai alerts Shu about the enemy; Shu fires the gun and realizes that Kido's ability is to manipulate gravity.

Shu holds Inori and the transmitter
When Inori jumps off to reach Shu, Shu fires the gun at the ground, so he can climb up the bubble to reach Inori. Shu asks Inori if it's okay to trust in her. While Shu pulls out a Void from Inori, Seiga kills his men who tries to snipe off Shu. Seiga gazes at Shu in amazement as Shu destroys the whole tower with his and Inori's power. After the whole event, Gai finds Shu and Inori. Gai asks Shu what he will do and when Shu does not answer, Gai tells him to follow his orders. Shu holds the transmitter and puts in his pocket before he walks.
Closing theme:
"Departures: Anata ni Okuru Ai no Uta" by the fictional band Egoist
Points of Interests
- Kido's Void ability is to manipulate gravity.
- Shu has use three Voids against GHQ so far: Inori's sword, Daryl Yan's cannon, and Kido's antigravity gun.
- Shu still has the transmitter from Seiga.
- Ending Credits has a slight change: Shu wakes up a with a glum face; Inori leads him.

Guilty Crown End Card - Ep. 4
End Card