The Window (1949)

At the age of 9, Tommy Woodry has a reputation for telling tall tales the latest one being that his family is moving from Manhattan to a ranch out west. When the landlord interrupts the Woodrys at dinner to show their about-to-be-vacated apartment, the Woodrys tell Tommy enough is enough.

Then that hot summer night Tommy decides to sleep on the fire escape outside the Kellerson's apartment, since it is a story higher and gets more breeze. Tommy sees the Kellersons kill a man. Tommy's parents and the police won't believe his story. But the Kellersons want to silence him.