A hundred pages might sound dautning, but a script is mostly white space. You read down the page, not across, if that makes sense. The general rule is one page of a screenplay is equal to one minute on the screen. Remember that the camera catches everything. One small nuance of a smile between charaters might be a three whole paragraph of prose in a novel, but in screenplay form it's only a sentence. Because the AUDIENCE supplies the emotion, not the prose.
Forget about creative adjectives and sweeping prose. A script has NO internal thoughts or lengthy descritions of any kind. Start thinking about your story in terms of dialogue and action. That's it. Make one of your characters a big dang liar and that will add subtext as well, which is far more necessary in a script than in a novel.
I find screenwriting easier than novel writing, frankly. Good luck to everyone. You'll love it or hate it by the end. There's pretty much no middle ground.
(edited for content, spelling)