When two young men are shot and killed in a car, Gwinnett County Homicide must turn to the survivors to learn the truth about what led to the shooting. In medicine, they call it the 'critical hour.' In criminal investigations, they call it 'the first 48 hours'. Ask any detective - they will tell you that if they don't have a lead, a suspect or an arrest within 48 hours, their chances of solving the case are cut in half. In a visual style that feels more like a TV drama than a reality show, The First 48 follows homicide detectives during these initial critical hours as they race against time to solve their cases. Every hour-long programme follows various detectives from select homicide teams as they track breaking cases, each with a running clock that builds pace as the 48 hours inexorably expires.