The Silent Planet was a small planet, covered in a thick atmosphere which blocked out nearly all light. The native species spent their lives in this mist, disembodied and isolated from each other. It was thousands of years after the planet was found that life was discovered, but even then communication was impossible. Indeed, the name was chosen because of the lack of communication. Eventually, the Silent Planet was ignored and passed into myths and legends.
At some point in its history, the Cardiff Space-Time Rift opened a connection to the Silent Planet. This connection was noticed by an individual with a mental illness, who wanted contact with others and was attracted by the sounds heard through the Rift. Coming to Earth, it tried to capture the singing it heard, but only killed its victims. Though it was eventually pulled back through the Rift, it fused with Ryan Scott, an autistic child who sang to isolate himself from the world. (PROSE: Into the Silence)