All names have been changed to protect the guilty.
The top story of a newscast is the one the news producer deems most important, most likely to grab the viewer and gain ratings points. It's the equivalent of above the fold in the newspaper world.
Way back in the day, around 1991, I was a VTR operator at a large-market TV station in NoCal. The shift usually consisted of logging, queueing, and putting story tapes in run order for the late newscast. 50 soundbites in 3 minutes.
Since broadcast news is a lot of hurry up and wait, there's always time to kill waiting for the up to the minute sports tape to be flung at you by the buffed, noneck sports intern.
One evening, there had been a large bust in the area. The goods were found growing in a small house trailer, walls covered with tinfoil, grow lights, floor littered with buds. SOP. There was a sheriff's deputy present at all times during the photographing of the evidence, so that there would be no pilfering. Shortly after the crew returned and the story edited, Jose the votog gave me the tape to rack. He winked, and said "We need to check the humidity in the film vault. And bring Bob with you."
When in the film vault, Jose pulled a spliff out of his pocket. We toked up and he told us the story of getting one over on the man. He had taken shots of the evidence from every angle he could aim from, and some that aren't taught in Videography 101, then left the trailer, smiling, as he walked back to the news van in his waffle-soled hiking boots.
I'm not sure where the story ranked in the newscast, but it was our top story of the night.