Undercover narcotics officer Nick Tellis chases a drug dealer through the streets of Detroit. Tellis shoots and kills the dealer when he holds a child hostage, but a stray bullet hits the child's pregnant mother, causing her to miscarry. Eighteen months later, Tellis is tasked with investigating the murder of an undercover officer, Michael Calvess. Tellis reluctantly agrees to take the case on two conditions: that he will get a desk job if he secures a conviction, and that he is partnered with Detective Henry Oak, whom Tellis has read about in the Calvess case file. The police chief accepts Tellis' conditions, but warns him about Oak's instability.