Filmed at the historic Hoyt Sherman Theater in Des Moines, Iowa, "Tonic Sol-Fa: Greatest Time of Year" highlights the foursome's musical artistry, showmanship and trademark humor as they perform a mix of holiday favorites and interact with the enthusiastic audience. The concert is intertwined with exclusive behind-the-scenes footage that showcases the chemistry among Tonic Sol-fa members Mark McGowan, Greg Bannwarth, Shaun Johnson and Jared Dove.