To save his own hide, petty hoodlum Benny Carbassa, the Nathan Detroit of Immortality, turns MacLeod over to an aging gangster determined to see MacLeod dead before he dies. In the midst of this, Anne returns, having convinced herself that MacLeod will open up in his own time and determined not to push him too hard. In flashback, we see MacLeod's first meeting with Benny, in 1938 at the Coconut Lounge, a club operated by two young brothers who are rivals for the same torch singer.

When Immortal Ceirdwyn and her mortal husband are gunned down by a street gang, she calls upon her skills as an ancient Celtic warrior to exact her revenge on the members of the gang, one by one. At the racetrack watching Richie's success at racing, MacLeod befriends a young pickpocket, the brother of one of the gang members, and learns of the killings. MacLeod, who has known Ceirdwyn since before they helped smuggle Bonnie Prince Charlie out of Scotland in 1746, feels he must stop Ceirdwyn and make her see that revenge is not the answer -- a lesson she helped MacLeod learn in the bloody aftermath of Culloden. In return, Ceirdwyn helps MacLeod see that, although loving a mortal can be dangerous for the mortal, it is the mortal who must choose whether to take the risk. MacLeod calls Anne. Meanwhile, Richie ""dies"" in a firey crash during a race, a crash that also takes the life of the champion, Basil.

In an episode filled with danger and compassion, Richie encounters Mikey, a huge Immortal of limited mental development and a fascination with trains. Richie takes Mikey home to MacLeod, who advises him that taking care of Mikey could be trouble. MacLeod remembers coming to the aid of a young Indian in trouble, when his help got the man killed. While MacLeod faces Tyler King, and Immortal who's coming after Mikey, Richie must find the maturity to take responsibility for Mikey's situation.

MacLeod's old friend Warren Cochrane is hiding a horrible secret he can't bear to remember. Realizing that an Immortal who won't remember what he is is soon a dead Immortal, MacLeod tries to help Warren by reminding him of the history they shared together, of their battles for Scotland's freedom, and of their mission to return Bonnie Prince Charlie to the throne. But MacLeod might have helped his friend more by letting the past stay buried.