Tony-winning actor David Alan Grier tells Stephen about his passion for medicine, his early efforts to become a musician, and shows off his silky singing voice. Watch David Alan Grier in "St. Denis Medical" airing Monday nights on NBC. #Colbert #Comedy #DavidAlanGrier #StDenisMedical #NBC #StephenColbert #TheLateShow Subscribe To "The Late Show" Channel: http://bit.ly/ColbertYouTube Watch full episodes of "The Late Show": http://bit.ly/1Puei40 Listen to "The Late Show Pod Show" podcast: https://