That same year, her husband diverted the USS Enterprise to the planet, ostensibly to confirm his discovery of a new synthetic food that could totally end the threat of famine on Cygnia Minor, a nearby colony. In fact, he diverted the Enterprise because he believed Anton Karidian, a traveling performer, was actually Kodos. He hoped Kirk, another of the eyewitnesses, would help him in his quest to bring Kodos to justice. She had reservations about her husband's claim that Karidian was Governor Kodos.
That night, after a performance of Macbeth, there was a cocktail party at the Leighton house. She was the hostess at the party, providing her guests with drinks. Kirk asked Martha where her husband was; she replied that he was in town and had called to say that he was coming home. Before taking an evening stroll with Lenore Karidian, Kirk apologized to Martha for leaving the party early.
After her husband was found dead, his body was returned to the Leighton residence. After covering his body, Martha commented that she believed her husband had found the peace that he didn't have when he was alive and questioned, if his suspicions were untrue, why he had been killed. Kirk promised to find the reason for his murder. Before leaving Kirk, with tears in her eyes, she expressed how much she would miss her husband. (TOS: "The Conscience of the King")