The Criminal Intelligence Unit (CIU) is a group of 30 experts who work to infiltrate the gangs operating within The Cook County Jail and gather information about gang activity in the Chicago area. This series follows CIU as it works with the Cook County Sheriff's Department to bust drug houses, confiscate illegal weapons caches and even solve cold case murders. One highlight of the program is the coverage of Operation Room Service, a sting which led to 100 arrests, more than $100,000 in narcotics and an arsenal of weapons.