Highlander: The Raven (1998)

Season 1: Episode 10

Lucy kills an actor with a gun, then tries to cut off his head. The police intercept her before she can succeed and the actor, Wilson Geary, disappears. In flashback we find out that Lucy's husband Marco was an Immortal, and Wilson supposedly used her to set up a trap for Marco and take his head. Wilson has another story, that Lucy seduced him and he only killed in self-defense. Amanda eventually figures out that the truth lies somewhere in-between: a jealous Lucy didn't intend for things to go that far with Wilson, but that he still used her to set up Marco. Now Lucy wants revenge, but upon confessing the truth decides to leave. Geary will have none of it, and kidnaps her. Amanda goes to his theater to rescue Lucy, and takes his head.