"Little Girl Lost" is an episode of the The Twilight Zone.
"Missing: one frightened little girl. Name: Bettina Miller. Description: six years of age, average height and build, light brown hair, quite pretty. Last seen being tucked into bed by her mother a few hours ago. Last heard--aye, there's the rub, as Hamlet put it. For Bettina Miller can be heard quite clearly, despite the rather curious fact that she can't be seen at all. Present location? Let's say for the moment--in the Twilight Zone."
"A couple, Chris and Ruth, are awoken by the distant whimpering of their little girl, Tina. Chris slowly gets up to see what the trouble is. Their dog, Mack, begins to bark from their back yard. Chris finds Tina's bed empty, though he can hear Tina's plea for help. Looking around the room, he says, "I'm here, where are you?" Mack barks again in the back yard.
Chris crouches next to the bed while trying to talk Tina out from underneath it, where he thinks she is hiding. He looks under the bed only to find that nothing is there. Chris can hear Tina (with a strange echo effect) and she can hear him, but neither can see each other. He explains to Ruth that even though they can hear her, their little girl is no longer with them.
Mack is now barking incessantly. Chris calls his physicist friend, Bill, for help and opens the door to let Mack into the house. The dog runs into Tina's room as Ruth, still in the room, watches it go under the bed. She bends over calling it back, but becomes quiet when she sees that it has disappeared. She can still hear the dog's barking (also with the echo now) and Tina's voice.
Bill comes over and examines the wall behind the bed. He taps the wall and finds an invisible portal to another dimension. He explains it by saying sometimes lines in our three dimensions end parallel with, rather than perpendicular to, the fourth dimension.
The adults try to call to Mack to guide Tina back, but their attempts fail. Finally Chris, despite Bill's warnings, leans into the portal and falls into the other dimension. Chris lands in a hazy, foggy, abstract place, where space and shapes are distorted, turning upside down and sideways. When Chris calls to Bill, his voice also echoes. Chris sees Tina and Mack and tries to call them towards him, since he is standing right near the portal. On the other side, he hears Bill's voice telling him to hurry up. Finally as Tina and Mack close in on him, Bill grabs them and is pulled back into the bedroom. Ruth takes the girl to another room.
Bill explains that Chris was actually only halfway in, despite Chris thinking he was standing up in the new dimension. Bill was in fact holding on to Chris the entire time. He was telling Chris to hurry because the portal was actually closing, and had Chris remained there for any longer than a few more seconds, he would have been cut in two as the portal closed with half his body in the other dimension. As Bill puts it to Chris, 'Another few seconds, and half of you would've been here, and the other half.....'" 
"The other half where? The fourth dimension? The fifth? Perhaps. They never found the answer. Despite a battery of research physicists equipped with every device known to man, electronic and otherwise, no result was ever achieved, except perhaps a little more respect for and uncertainty about the mechanisms of the Twilight Zone."
Preview for Next Week's Story
"Next week we again borrow from the considerable talents of Charles Beaumont, and we take a fast trot on the wild side. Picture if you will a man who wakes up in a strange world, knows everyone, knows every place, feels very much at home. The strangeness comes from the fact that no one knows him. Try this one for size on the next Twilight Zone. It's called "Person or Persons Unknown".
- Rod Serling (Narrator)
- Robert Sampson (Chris Miller)
- Sarah Marshall (Ruth Miller)
- Tracy Stratford (Tina Miller)
- Rhoda Williams (Tina's voice)
- Charles Aidman (Bill)
- Main article: List of memorable quotes from the first series