So...what's your story about?
It's the most dreaded question in the business, and you NEED to know the answer. Maybe you're at a party, or in an elevator with an executive, or busking out on the streets, but someday those five words are going to come spraying at you. How you answer will determine whether you drive home in a brand new Corvette, or ride sullenly on the midnight train to Georgia.
So...how the hell do you describe your idea?
First of all, don't recap the plot. When an exec (or really anyone) asks about your story, they don't want to hear the beats. They want the gist. And the gist needs to be 30 seconds of hand-spun gold. That means you don't have time to go into the quirky sidekick or the Act 2 twisteroonie. In the space of one to two sentences, you need to hook the listener hard.
Basically, you need to land them with your Theme.
Imagine that you are pitching Everybody Loves Raymond. If you go through an episode line by line, you'll end up boring your audience before the first act break. Instead, distill the show down to it's core: How do you go about being an adult when your parents still live next door?
Once you find the theme, it's rather simple to paint a decent picture. Let's try a few examples.
24: America's best Counter Terrorist Agent is about to have the worst day of his life.
Timeless: Elon Musk built a time machine, and terrorists stole it to rewrite history.
Lucifer: When the Devil takes a vacation in Los Angeles, he learns that being Good isn't all that bad.
Distill your idea down to its essence, not the building blocks of any particular episode.
Now get to writing!