No Regrets is the eighteenth episode of the fourth season of the television series Agents of S.H.I.E.L.D. and the eighty-fourth episode overall.
The truth behind Fitz's turn could bring down all of S.H.I.E.L.D..
In the Framework, Leo Fitz's one regret was never making amends with his father, and with that removed, his father molded him into a callous man who should not indulge in doubt or worry, as they are feminine nonsense and have no place in his head. As Fitz conducts an investigation into the spy in HYDRA, he finds himself questioning his choice to kill Agnes Kitsworth back in Ogygia.
After Fitz "interrogates" Daisy Johnson, Madame Hydra asks him to leave. All alone, Aida tells Daisy that if she simply divulges where the others are, she can make Lincoln Campbell return and the two of them can live a life together in peace, which Daisy refuses knowing it would never be the real Lincoln. Through the vents in their holding cells, Daisy learns from Holden Radcliffe that Fitz killed Agnes Kitsworth. Daisy, in shock, can't believe such a thing about her friend until Radcliffe explains that one sentence in Fitz's altered timeline in the Framework changed the developmental course of his character. As a way of revenge for killing Agnes, Radcliffe tells Daisy of a backdoor he installed to escape the Framework that Aida is unable to disable, though she likely has it guarded.
Jemma Simmons informs Jeffrey Mace that he is in fact in a simulated reality generated by Aida to rewrite his sense of reality. Grant Ward, uncertain if Simmons is mentally ill, keeps a watch on her and apologizes for whatever his counterpart may have done. Alphonso Mackenzie, having joined the S.H.I.E.L.D. resistance gets intel on a repurposed radio which Mace and Phil Coulson use to infiltrate a HYDRA "Enlightenment Camp" to free an undercover agent — Antoine Triplett, a S.H.I.E.L.D. agent who died in the real world.
They are tracked there by Melinda May, who uses a super serum to fight Mace, but it wears off. Coulson attempts to save one of his former students Chris Adler, who he sees being held in a nearby brainwashing center, and Mace follows him into the building to help. May authorizes a Quinjet to shoot down the building, and May enters the rubble to ensure that Mace is dead.
She finds him stopping debris from crushing the student, with Coulson and Triplett helping other children escape the building. May is horrified to find children being victimized by HYDRA, while they are undergoing the Faustus method. With the others evacuated to safety, Mace dies while attempting to hold up the crumbling debris, killing him in the real world as well.
May realizes too late that in serving HYDRA to make up for the tragedy at Cambridge, she became a blind tool of an oppressive force and allowed a true hero to die. Turning on HYDRA, May sneaks a Terrigen crystal to Johnson, so she can gain her Inhuman abilities within the Framework.