When veteran Nashville homicide detective Tim Slater is ambushed and murdered outside a local Music City cafe, the investigative resources of the Nashville Police Department go on high alert, mobilized to track down his killer. During Sergeant Mike Neal's intense investigation he discovers Detective Slater had a six-figure life insurance policy owned not by his wife but by his ex-wife, who has made it clear, this is no one else's business. Two days after Slater's emotional Line of Duty funeral, Sergeant Neal is pursuing leads in his investigation when he receives a call from Detective Slater's widow stating she's discovered a small digital recorder in her husband's personal items at home. She tells Neal she's certain he'll want to hear what's on it. The recorder's revealing message compels Sergeant Neal to visit Detective Slater's retired former partner whose personal revelations on a three year old closed case set in motion a high-velocity roller coaster ride that drives the investigation toward Slater's killer and a shocking disclosure no one could have predicted.