The worse possible scenario always occurs. This makes your story more interesting and more dramatic at the same time.
In “Mulan,” a young woman disguises herself as a man so she can fight in an army. What’s the worse-case scenario? That she’ll be discovered as a man and that’s exactly what happens.
In “Galaxy Quest,” aliens have mistaken the TV stars of a Star Trek-like show as real people so what’s the worst that can happen? They have to admit that they’re actors and not real starship crew members after all.
In “Tootsie,” Dustin Hoffman disguises himself as a woman to get a job on a soap opera. What’s the worse that can happen? His disguise is revealed.
Whenever you create something in your story, think of the worse that can happen. If a character hides something, it has to be discovered. If a character has a secret, that secret must get leaked out. If a character fears something, that fear must confront that character.
Your story must complete its implicit promise. If you show a gun, then that gun must be used such as in “Thelma and Louise.” If you show a gun but never use it, it sets up false expectations. If you just have a character pull out a gun for the convenience of the plot, it comes across as phony and less satisfying.
As the audience, we cringe, but we want to see the worst that could happen to the characters because seeing how they respond is half the fun of a movie. Go to extremes. Make your characters suffer highs and lows on the emotional scale because then you’ll take your audience on an emotional high and low.
Think of your story as a roller coaster. Would anyone want to ride a roller coaster that was flat, safe, and smooth, or do people want to ride a roller coaster that has giant dips, hills, and turns?
Make a promise to the audience and then keep it by showing the worse case scenario. It may make your writing tougher, but it’s what audiences really want to see.