A discharged U.S. serviceman is found dead on a Philadelphia street and a pair of homicide detectives struggle to solve a crime with no witnesses, no leads, and no family to speak for the victim. Only Son takes you through the streets of Philadelphia, from the violent streets of Kensington, to the vibrant business district of South Philly. From the courtrooms of the Criminal Justice Center, to the hallways of Police HQ, and many places in-between.