while mal, zoe and jayne may handle most of the plot and action, simon and river tam are the other real heartbeat for the show. simon gave up a promising career as a doctor to save his sister, river, from some creepy alliance experiment. the two are fugitives and while that complicates the lives of everyone else on serenity, it also gives them all purpose. what was the alliance doing to river? what secrets are in her head? watch the show and then watch the movie. seriously. you'll love it.