Kryten quickly created a prism laser that was fired at a mirror in Captain Hollister's quarters. This created a gateway to a mirror universe which Rimmer stepped through before the laser failed, needing to be repaired.
Rimmer found that in this universe, he was the ship's commanding officer. He reveled in this role, humiliating the mirror version of Frank Hollister who was a lowly errand boy. He was also delighted by what he found when he looked under his bedclothes. The woman he assumed to be his lover turned out to be a nun.As he went in search of a scientist to develop an antivirus, he made his way to the laboratories. Here he met the Mirror Kochanski, a surly and ignorant secretary. She insisted that he would need The Professor. He turned out to be an alternate Cat, who was indeed an opposite, being incredibly well-educated and insightful. He quickly analysed the viral specimen that Rimmer had brought and identified the antivirus as an alkali called Cesiumfranciolithicmyxialobidiumrixydixydoxidrexidroxhide. He wrote it down on a long piece of paper for Rimmer.
When Rimmer returned through the repaired mirror, he discovered that the virus had spread all over the ship and that the cure he had brought had turned back into the virus. He tried to follow his crewmates back into the mirror universe, but the prism laser had corroded beyond repair. (RD: Only The Good...)