 Greg Edmonson composed the musical score for the series . He stated that he wrote for the emotion of the moment . However , one reviewer averred that he also wrote for the characters , stating : " Edmonson has developed a specialized collection of musical symbolism for the series " . To help illustrate the collection , the reviewer gave key leitmotifs , or " signatures " , various names , noting that " Serenity " recalls the theme of the show and is used when they return to the ship , or when they were meeting clandestinely ; it was " the sound of their home " . The slide guitar and fiddle used in this piece are portable instruments which fit the lifestyle of the crew : " the music they make calls up tunes played out in the open , by people who were hundreds of miles away yesterday . ' Serenity ' conjures the nomadic lifestyle the crew leads and underlines the western aspect of the show . " Another emotional signature was " Sad Violin " . It was used at the end of the Battle of Serenity Valley , but also helped set up the joke for when Mal tells Simon that Kaylee is dead in the episode " Serenity " . The most memorable use of " Sad Violin " , however , is at the end of " The Message " , when the crew mourned the death of Tracey . This was also the last scene of the last episode the actors shot , and so this was seen by them , and Edmonson , as Firefly 's farewell . To denote impending danger , " Peril " was used , which is " a low pulse , like a heartbeat , with deep chimes and low strings " . The reviewer also noted character signatures . The criminal <unk> has his own signature : Eastern European or Middle Eastern melodies over a low drone . Simon and River 's signature was a piano played sparsely with a violin in the background . This is in contrast to the portable instruments of " Serenity " : the piano is an instrument that cannot be easily moved and evokes the image of " the distant house and family they both long for " . The various signatures were mostly established in the first pilot , " Serenity " , and helped enhance the narrative . 
