Following the explosion that gave him the power to create matter from nothing, Eli escapes. The rest of the team struggles to deal with the mysterious disappearances of Coulson, Fitz and Robbie. Simmons is taken to see a subject who has been undergoing Terrigenesis gradually. 

May wants to open the Darkhold to see it it will help them figure out what happened to Coulson and Fitz, but Mack objects. He wants to contact the Chinatown crew to see if they know where Eli is, but Director Mace refuses to let him go. Mack jumps on a motorcycle and takes off anyway.

Fitz and Coulson find each other right after getting blasted with the fallout of Eli's particle generator. Mack and May enter the room, but they cannot see or hear Fitz and Coulson. The same thing happens to Robbie when he tries to stop Eli from killing some S.H.I.E.L.D. agents; he's unable to do anything because no one can see or hear him.

Coulson, Fitz and Robbie follow Mack and May back to S.H.I.E.L.D. Fitz thinks they're trapped between dimensions and worries that S.H.I.E.L.D. will tell Simmons he's dead. Fitz eavesdrops on Director Mace as he calls Senator Nadeer and demands Simmons' return. Senator Nadeer refuses to let her go until she finishes her work. 

Robbie feels cold and sick as he struggles to control Ghost Rider, who explodes out of his body and possesses Mack. Daisy jumps in Robbie's Hellcharger to chase down Mack. 

May gives Radcliffe the Darkhold and begs him to read it, claiming only he can understand the science. However, Radcliffe argues that it's too much for the human mind to bear. Simmons introduces herself to the Terrigenesis subject, whose casing begins to crack. Mack confronts a member of the Chinatown crew, his eyes glowing with Ghost Rider's fire. 

Radcliffe confesses to May that Aida is an android. May asks him to use her to read the Darkhold since she is the only one there who isn't human. Daisy tracks down Mack and asks him to come with her, but Mack transforms into Ghost Rider before her eyes. 

Robbie is revealed to have been sitting invisibly in the passenger seat of the Hellcharger while Daisy was driving after Mack. He tries to give Daisy directions to the Chinatown Crew's warehouse, and the Hellcharger helps him convey his message despite his being caught between dimensions. 

Fitz tries to beg Aida to read the Darkhold, much to Coulson's disbelief. Fitz tells Coulson that Aida is an android. Simmons manages to remove part of the casing covering the Terrigenesis subject's face. As soon a she does, she is dragged out of the tent. 

Robbie confronts Ghost Rider, who speaks to him using Mack's voice in Mack's body. Aida and Radcliffe build an inter-dimensional portal to help Fitz and Coulson cross back into their world. Robbie finds himself being pulled down into hell as he argues with Ghost Rider. After a brief struggle, Coulson and Fitz burst across the threshold. Robbie convinces Ghost Rider to leave Mack's body and re-enter his, but once it happens, he disappears. 

Fitz and Simmons reunite. Coulson asks Daisy to follow up on a lead on Eli's location. Mack is sitting alone when Robbie bursts through the interdimensional portal. He asks Mack to help him settle his last score. While Radcliffe basks in the victory, Aida continues playing with the magic she learned from the Darkhold, constructing a model of a brain.