As the episode begins, we see Captain Kirk attending a performance of Macbeth with a friend. Kirk seems relaxed and mildly interested in the play, but his friend is obviously tense and on edge. He implores Kirk to look closely at the actor playing Macbeth, and listen to his voice. Kirk doesn't notice anything remarkable about him, but his friend insists that the actor is Kodos, the Executioner (cue the dramatic music).
One person who isn't feeling the love is Riley, on lonely late night duty in engineering. He passes the time chatting with some crew members in the rec room, including Uhura, who decides to cheer him up by singing a song to him. While he is distracted, someone sneaks in and poisons his milk, and while Uhura is caroling about being "somewhere beyond Antares", Riley is choking and falling unconscious to the floor.