S03E17: The Stalker

Following her ugly break-up with Dalton Lowne, Mac has reason to believe that he's stalking her -- until he's killed during an apparent car-jacking and the stalking continues. Much to Harm's dismay, the strain of the two events pushes Mac to the edge -- and to the bottle. Concerned for Mac's safety and sobriety, Harm intensifies his search for Mac's tormentor before he causes her bodily harm.