- You may be looking for the audio story.
The Prisoner was a creature who was imprisoned inside an asteroid-like prison. When travelling through a region of the universe, a tear in space and time opened up in front of it and in front of the physics classroom at Coal Hill Academy on Earth.
As Charlie opened the door to the classroom, the prison, along with the Prisoner, flew into the classroom and caused a huge explosion that threw the entire classroom out of space and time. The Prisoner had nothing left for himself, all he wanted was to die. He forced Charlie, April, Ram, Matteusz and Tanya to confess truths to the point that he was destroyed. This returned them and the classroom to Coal Hill. (TV: Detained)