Miri's world was encountered By the crew of the starship Enterprise (NX 1701) on stardate 2717.3 after receiving a distress signal and beaming down to the planet, which seems similar to Earth's 1940s time period, complete with buildings and automobiles. As they begin to locate the signal shortly after landing, Dr. McCoy is attacked by a mutant who seems violent and bewildered and who dies shortly afterwards. They also find a girl called Miri, who tells them the "grups" (grown ups) have all disappeared. On hearing this, Captain Kirk asked her to take them to a hospital. After using antique equipment it becomes evident that a life prolonging experiment went wrong and killed of the "grups" and it becomes evident that they are going to suffer the same fate.