- "Radcliffe built a humanoid robot that's about to attack the base."
"Why would he do that? Has he watched no American movies from the '80s? Robots always attack."
"I've been saying that all day."
"Smart people are stupid."
"All right, gear up. The robot apocalypse is finally here."
- ―Alphonso Mackenzie and Yo-Yo Rodriguez[src]
In an attempt to rescue S.H.I.E.L.D. agents Phil Coulson and Leo Fitz who were trapped between dimensions, Holden Radcliffe and Aida were exposed to the infinite knowledge of the Darkhold, which corrupted them. As a result, Radcliffe became obsessed with the idea of getting the Book of Spells for himself and achieve his dreams of immortality. To that end, Radcliffe secretly reprogrammed Aida so that she could help him steal the Darkhold, which was in S.H.I.E.L.D.'s hands. Radcliffe and Aida also replaced S.H.I.E.L.D. Agent Melinda May with a Life-Model Decoy, which could also help them to fulfill their plans.
Director Jeffrey Mace and Coulson feared the consequences of a misuse of the Darkhold. They decided to hide the Book of Spells and kept it cloaked in Mace's office, and instructed Radcliffe and Fitz to erase Aida's memories so that the knowledge she had of the book would disappear. However, Aida rebelled against Fitz and Radcliffe and attacked them before leaving the Radcliffe Residence. Meanwhile, Fitz discovered the body of Agent Nathan B. Nathanson who had been murdered by Aida.
In response to Aida's rebellion, Coulson gathered his team in the Playground along with Radcliffe, although Alphonso Mackenzie was keen on taking the scientist into custody. Radcliffe explained that the Darkhold was to blame for Aida's behavior and that the android only wanted to become a living being and feel real emotions.
While S.H.I.E.L.D. unsuccessfully looked for reports of Aida, the android simultaneously called all the phones of the S.H.I.E.L.D. agents. Coulson picked up the call and listened to Aida as she demanded the Darkhold to be given to her. When Coulson refused, Aida cut the power in the Playground. Fitz and Radcliffe left to restore the power while Mackenzie went to enlist Yo-Yo Rodriguez's assistance in the fight against Aida.
Coulson remained with Melinda May LMD, still unaware of her true nature, and as they walked the corridors of the Playground, they encountered Aida who had infiltrated the base. Aida attacked Coulson, who managed to punch her in the face, only for Aida to violently retaliate and knock Coulson unconscious. May's LMD, who was programmed to act like the real Melinda May, tried to attack Aida as well, but Aida simply deactivated her. She then cut May LMD's skin on the face to make believe she had fought and lost to Aida.
While Fitz and Radcliffe worked on restoring power in the Playground and discussed what could have caused Aida's rebellion, Coulson and May LMD found themselves locked in a room, unable to go after Aida. In the meantime, Rodriguez and Mackenzie patrolled the Playground in search of Aida, but the android overrode the control systems of the Quinjets, causing the planes to attack them, forcing them to hide.
Thanks to May LMD's Backscatter X-Ray Eye Implant which data she had access to, Aida learned the location of the Darkhold: Mace's office. She found the book and successfully reclaimed it before attempting to leave the base. However, she was unable to escape as Fitz had reprogrammed the system to keep her from leaving with the Darkhold. Coulson and May LMD, who had been released, joined Fitz and Radcliffe and convinced Aida to surrender. As Aida insisted that she had not killed anyone in the base, Mackenzie came behind her and beheaded her with his Shotgun-Axe, thus securing the Darkhold.
Back to the Radcliffe Residence, Holden Radcliffe activated another Aida and remained obsessed with the idea of stealing the Darkhold for himself so he could achieve his immortality fantasies. Since Aida failed to reclaim it, Radcliffe counted on Melinda May LMD to eventually seize the Book of Spells.
Aida's severed head was reclaimed by Leo Fitz, who intended to investigate the data contained in it to figure out what had caused Aida's rebellion. Despite Jemma Simmons' calling it an obsession, Fitz discovered that the one responsible was no other than Radcliffe himself, which led to his arrest by S.H.I.E.L.D. However, Radcliffe had replaced himself with a Life-Model Decoy, thus evading capture.
The Darkhold still being a source of malevolent desires, Phil Coulson entrusted it to S.H.I.E.L.D. Agent Billy Koenig who hid the Book of Spells in the Labyrinth with the help of LT Koenig and Sam Koenig. However, this led Radcliffe, who had allied himself with the Watchdogs, to kidnap Billy in another and this time successful attempt to steal the Darkhold.