Nelson Riddle was quite possibly the greatest arranger in the history of American popular music. Over the course of his long and distinguished career, he was also a popular soundtrack composer, a conductor, a trombonist, and an occasional hitmaker in his own right. He worked with many of the major pop vocalists of his day, but it was his immortal work with Frank Sinatra, particularly on the singer's justly revered Capitol concept albums, that cemented Riddle's enduring legacy. Riddle was a master of mood and subtlety, and an expert at drawing out a song's emotional subtext. He was highly versatile in terms of style, mood, and tempo, and packed his charts full of rhythmic and melodic variations and rich tonal colors that blended seamlessly behind the lead vocal line.