The murder of a fellow MPD police officer, Don Eckler, has Dwight and company partnering with Internal Affairs to complete their investigation of the deceased cop.
As the investigation progresses, Dwight learns IA's inquiry began before Eckler's death, due to alleged white supremacist ties and involvement in arms dealing. Determined to clear Eckler's name of any wrongdoing, Dwight pursues the case for all the facts.
In the meantime, Dwight's partner, Charlie "Whitehead" White, is partnered with Lt. Rice, who uses her own special brand of motivation to elicit the more motivated and productive side of Det. White.
At Eckler's wake, Dwight initiates an a-cappella singing of "When the Saints Go Marching In," and is quickly joined by the many friends, family and fellow officers close to Eckler.
In the end, the death turns out to be the result of Eckler's nephew's involvement with a white supremacist group, which Eckler had tried to coax his nephew out of, only to be killed. This truth clears his name and allows his family to have a funeral fit for a hero, complete with an honor guard.