"Miri" shows that episodes with children need not be awful. Responding to a distress call Enterprise discovers an exact duplicate of Earth. Kirk takes a landing party down to find cities in dust, the signal set on automatic long ago. McCoy examines a broken tricycle and is accosted by a hideously deformed humanoid who dies after Kirk hits him several times, burning himself out as if aging centuries in minutes. A noise draws them to Miri, a young woman terrified of the landing party, and Spock discovers lots of other children hiding among the decay but no adults. Miri explains that the Onlies were left to fend for themselves after all Grups died in diseased agony in the Before Time.

Soon the landing party breaks out with early signs of the disease. Trapped on the surface with only days to live ("None of us feel alright!") they use ship's computers to unravel the medical mystery, a Life Prolongation Project of cascading illness that went horribly awry. Spock and McCoy develop an antidote but cannot test it after the Onlies grupnap Rand and steal the "small boxes they talk into" forcing Kirk to confront them, yelling in class like a bad student. Miri herself now shows symptoms and with her help ("tell him Jim!") Mr. Lovey-Dovey convinces the Onlies to let him help them. McCoy injects himself with the cure moments before Kirk arrives with the communicators, but he recovers before their eyes and all ends well.

Masterful direction leads to magnificent acting by Kim Darby as Miri and Michael J. Pollard as Jahn. Neither "child" actor (aged 19 and 27 respectively) appears pre-pubescent but together they secure a plot that could otherwise have easily gone terribly awry, helped by John Megna as Bonk-Bonk Two-Jobs and TOS HITG Ed McCready as Mr. Tricycle. A slew of production children color the background appropriately including Shatner's own daughter smiling creepily as her old man gets beat upon. (And credit many a nightmare to Louise, surely one of the best "boo" moments of the series!)

This fan favorite episode stands despite the inexplicable and completely irrelevant plot device of an alternate Earth (necessary to setup plot parallels yes, but "Bread and Circuses" handles this sort of thing far more deftly). One can also forgive convenient coincidences such as Enterprise arriving right as three hundred and one-half years of food are about to extinguish. But it's still a warm, thought-provoking story untouched by time even as the Onlies pass. Of course it's a good thing.