Formed in 2010 at the Church of the Good Shepherd on Chicago's South Side, The Good Shepherds are a gospel group comprised of one tenor and two baritones, all classically trained with divergent music tastes. They're performing with piano accompaniment at 2:30 p.m. Sunday as part of the latest installment of Sounds of the South Loop at Second Presbyterian Church. Tickets are $15 in advance and $18 at the door, with discounts for students and seniors.