Melanicus was a native of Althrace, a solar system in which all the planets have been joined together, and which contains one of the most advanced civilisations in the galaxy. He was of the race of Kalichura, one of the many species who lived in the system. He developed a passion for war and destruction, and tried to conquer Althrace. Defeated, he fled to another dimension, from which he made contact with the third century Earth despot, Catavolcus. The tyrant king performed a magic ceremony to bring Melanicus into Earth's dimension, and the two forged an alliance.
While travelling through time, Catavolcus and Melanicus briefly ended up on Maruthea, a space station at the centre of the space-time vortex. There they were involved in a large bar room brawl.
Before they could carry out their plans to conquer the Earth, Merlin the wizard intervened, reversing the spell that had summoned the demon, banishing him back to the formless, black void that he had come from.
The Prime Mover who plays the Event Synthesizer which harmonizes the patterns of time accidentally hits a discordant note for the first time in centuries. This fractures the pattern of harmony, creating a gap in time, allowing the demon Melanicus to escape the formless void he has been trapped in for the last thousand years. He sweeps the Prime Mover aside, and strikes the keyboard, sending temporal ripples through the centuries.
Melanicus considers his next move, and suggests he might make himself ruler of all time. The Prime Mover protests, stating that there are those who will stop him. This convinces the demon that he should hide in the abyss of time, "beyond the reach of all", continuing to send chaos and death through all reality. He uses the Synthesizer to transport him and it away to his hideaway.
The Doctor and his companions Justin and Shayde enter the nightmare dimension Melanicus has hidden himself in. After getting on a funfair ride, the Doctor and Shayde head down the tracks towards what appears to be a giant version of Melanicus.
Shayde shoots the hideous visage that confronts them, and it explodes, having been nothing more than an illusion created by the Synthesizer.
Having given up their fruitless search of the insane reality Melanicus has hidden himself in, the Doctor and his companions travel to Althrace, where they are told of his origins. The the various High Evolutionaries combine minds to freeze time itself.
With time frozen, the Doctor and Justin are able to pinpoint Melanicus' hiding place. They travel to the devastated Earth, where they can hear music coming from a ruined church. Entering the building, the witness the Prime Mover playing the Event Synthesizer. But then the doors slam shut behind them and as the Mover strikes the keys, the air itself seems to turn evil. Justin snatches the Doctor's hat from his head, scoops up water from the font, and races forward to throw it into the Prime Mover's face. The man screams in agony, and the facade drops away to reveal Melanicus. He attacks Justin, breathing fire as if he were a flame-thrower. Then, while the knight is distracted saving the Doctor from a zombie, Melanicus sneaks outside and begins to climb the church's bell tower. But as he reaches the top, he is confronted by Shayde, who shoots out both his eyes. In agony, the demon looses his grip, and plummets down the side of the tower. He catches himself on the edge of one of the stained glass windows, but inside the church Justin spots the demon, and he plunges through the glass and impales Melanicus on his sword, killing him.