Dalton Lowne, Mac's ex, is found dead after she had an argument with him and left his place. This makes Mac a suspect in his murder. Later, Mac's home is vandalized with a message that could have only been from a stalker. Detective Costa, last seen in the episode "King of the Fleas", investigates.
At the same time, Admiral Chegwiden's daughter Francesca visits from Italy - and gets into a fender bender with Harm.