S3·E19 Death Watch

Mac arrives at Harm's apartment and is surprised to see that he has forgotten she was coming over and that he is getting to leave with a firearm. Stalling him, she gets him to tell her the story 2 years ago of the murder of his then-girlfriend, Lt. Diane Schonke, an Academy classmate, after her ship, the USS Seahawk docked in Norfolk. When Harm shows Mac a picture of Diane, Mac is stunned to see that Diane looks just like her.

When Harm tells Mac that he believes he has finally figured out who the real murderer is (Agent Turque) and that he intends to confront him, she gets him to initially agree to take her with him. Harm however tricks her and drives off, leaving Mac behind standing in the rain. Desperate to find Harm before he does something he'll regret, Mac calls Bud to meet her at JAG. Bud was an Ensign on Diane's ship and was one of the people who found Diane's murdered body. Bud tries to help Mac fill in the gaps and helps Mac learn that Agent Turque isn't the murderer.