After their homeworld suffered an ecological disaster that threw the planet into an ice age, the survivors of the alien race known as the Kohl placed themselves in a state of suspended animation that was to last fifteen years before they could be rescued. The minds of these five individuals were placed inside a virtual environment, allowing their minds to remain active and healthy during their hibernation. Unfortunately they had not foreseen that the feedback between their minds and the network would create a nexus for their darkest fears; essentially, they were so afraid that something would go wrong that the Clown, a malevolent manifestation of their worst fears, was created from their own fear of death, turning their dream state into a violent and torturous environment.
The Clown demonstrated mood swings and erratic behavior. For nineteen years he tortured the inhabitants of the network, killing three of them by subjecting them to the 'illusion' that they were being placed in a guillotine, but at the same time refusing to let them leave as that would end his own existence. The environment was that of a circus, with different characters such as a little woman and a spectre.
In the year 2372, the USS Voyager discovered the Kohl homeworld and detected the stasis pods underground, beaming them aboard for examination. Two of the five sleeping Kohl were long dead and the system would not allow the others to awaken, so Harry Kim and B'Elanna Torres were chosen to enter the virtual environment to determine what was wrong, communicate with the sleeping Kohl and find a way to revive them. The Clown was overjoyed to have new 'guests' and would not allow them to leave, threatening to kill Kim if he tried to interfere with the system. Viorsa, one of the Kohl, told him that if he did, Kim's shipmates would turn off the program. Having permitted Torres to leave to explain the situation to the rest of the crew, The Clown subsequently turned Kim into first an old man and then a baby, nearly forcing Kim to relive a memory where he witnessed people having to undergo extensive surgery after an accident. Although Captain Janeway attempted to negotiate with the Clown by sending The Doctor into the environment – as The Doctor was a hologram himself The Clown was unable to tap into his psyche – their attempts to negotiate were unsuccessful, resulting in The Clown killing Viorsa when he found him helping the crew as they attempted to shut down the program.
The Clown was tricked into releasing the Kohl and Harry Kim in exchange for Janeway. However, while they connected her mind to the system, they were able to configure it so that she remained conscious, her mind linked to the system without actually becoming part of it, while a hologram was used to fool The Clown into believing she was really there. As the system shut down around him, The Clown admitted his own fear before disappearing into darkness.