There's a clever and little-seen comedy called "Twenty Bucks" that follows the path of a $20 bill as it passes from one person to another — a newlywed, a gangster, a struggling author and so on. The idea of the film is that the same object, in different circumstances, can have any number of impacts on any number of people.
One could make a much more sobering film with the same basic premise, substituting a piece of plastic for a $20 bill. Seriously, the last time you threw a plastic bag or bottle cap into the trash (or on the ground), did you imagine where it would go next?
The journey of a plastic scrap can start on the sidewalk and move through the park, into the storm drain, onto the beach and finally into one of the massive gyres of plastic at the bottom of the ocean, where it breaks into particles and begins a new journey into the mouths of fishes and onto the plates of meat-eaters.