A serial killer identifying himself as a Good Samaritan – shortened by police to "GOOD SAM" – is loose in St. Louis, Missouri, targeting child sex offenders. Supervisory Special Agent SOMMER POTTS and her team must put their personal morals aside in order to catch this killer and bring him or her to justice. However, an unexpected turn of events leaves Sommer on the sidelines and her team struggling to pursue the killer on their own. This unforeseen circumstance could be the end of Sommer's career. Now her team must be able to function properly without her leadership and bring this "Good Sam" to justice.