A gunman kills volunteer police officer Laura Grillo in her suburban Dallas home. Investigators must link a bombshell accusation to a game-changing email with a diabolical mastermind who thinks he can outsmart the law. [also shown as S6:E14]

Bookkeeper Barbara Iske fails to arrive on time at the Michigan home of her wealthy client; five hours later, she's found executed in the driveway of that same client; ultimately, police reveal that Barbara's the victim of a dark family conflict. [also shown as S6:E18]

Devoted father and aspiring boat captain Tray Phelps takes his last breath, murdered just steps from his front door; with no immediate leads, it's up to Missouri investigators to find the murderous manipulator at the heart of a sordid family plot. [also shown as S6:E19]