[Anarchy]

You should say "following a story line", when you add the behind any word , it means one specific kind of that thing , the story line is not a general term

:e405:.

Thanks for your tip dude.But I think the storyline is correct as I, in my previous post, referred to movie watching and here storyline means "movie storyline" and has specific characteristics.look here for example:
storyline - definition of storyline by the Free Online Dictionary, Thesaurus and Encyclopedia.

storyline

noun narrative, plot The surprise twists in the storyline are the film's greatest strength