When Holmes and Watson investigate a murder, they find themselves in the crosshairs of one of New York City's deadliest gangs. Holmes' behavior becomes increasingly erratic when he secretly interacts with a mysterious woman.

Season 5 ends with Holmes and Watson pursuing an elusive criminal as a gang war erupts in New York City. While the NYPD works to contain the violence, the two investigate the murder that appears to have ignited the city-wide conflict and discover that a familiar face is pulling the strings.