The Doctor, Jo and Tyler are brought into the throne room. A masked figure emerges and identifies himself as Omega. Jo and Tyler are led away and sealed off in a room.
Omega was the stellar engineer who created the supernova that powered the Time Lords' time travel experiments. He was thought destroyed but fell through the black hole into a universe of anti-matter. He is bitter and enraged by what he sees as the Time Lords' betrayal. Omega is able to create a universe inside the black hole through pure thought. He now demands the Doctor's help to defeat the Time Lords.
Omega is alerted to new arrivals. The second Doctor, the Brigadier and Benton have arrived with the whole of UNIT HQ. The Brigadier is outraged when he sees that the building has been transported to what he thinks is a beach. He goes to get help. Benton and the Doctor are quickly caught by gel guards.
The Brigadier finds Ollis. They watch the gel guards escort the prisoners into Omega's lair.
Omega quickly realizes who the second Doctor is and is angered at the deception. He has them locked up with Jo and Tyler while he ponders their fate.
The Doctors explain to the others that Omega has control of the black hole singularity and is using it to create the world out of sheer will. They're not sure they can oppose him but Jo gets them to combine their wills to create a door out of the prison.
The Doctors finds their way to the singularity chamber and confront Omega. They tell him to either let them plead his case to the Time Lords or they will combine their wills to destroy him.
Omega has them fight his dark side. The third Doctor finds himself grappling with a hideous monster.
Jo, Benton and Tyler, chased by gel guards, find their way outside and are met by Ollis and the Brigadier. They manage to escape Omega's guards.
The Chancellor persuades the first Doctor to go into the black hole to help his other selves oppose Omega.
Omega's dark side gains the advantage over the third Doctor and begins to strangle him…