“The Valkyrie,” originally aired January 31, 1997. Nostalgia and spoilers within.
Didn’t we already have the Russian-leader-killed-by-a-prostitute plot? But this time, the Immortal and the prostitute are the same, the prostitute is ACTUALLY the assassin, and the Immortal wants him dead because he’s a threat.
But Joe, Methos, and Duncan are just doing some classical Highlander boxing–in honor of Charlie. Aww. And the assassin happens to show up at the scene, and she (Ingrid) knows Mac back from where they were anti-Nazi together. And later when Methos and Mac are out buying newspapers together (lol, ~dating the show~), Mac sees an ad for some white supremacist group, and he realizes that Ingrid must be there to kill their leader. Ugh, this episode is going to be Too Real this election season.
Anyway, she tries to assassinate Mr. White is Right, and Mac stops her and therefore gets framed. He’s surprised that Ingrid’s become an assassin because back in WWII, she didn’t like the thought of killing mortals. But since they missed their chance at killing Hitler, she tries to make up for it by killing everyone who could become Hitler.
So the guys all have a debate about history v. free choice, and nobody knows what to do. Mac is all ready to defend her forever, but then she shoots a cop. So he feels he has to stop her, but we spend the rest of the episode feeling bad because Racist Politicians are Bad, but Killing is Bad, and everything is bad.
In sum, killing is never the answer. LEARN IT. For a show predicated on killing, this is very pacifist.