to gain total control of their minds. The first officer assembles a security team, but the colony's force field blocks transport and communication. Unaware of events on the ship, Kirk decides to secretly test the neutralizer on himself, with Noel at the controls. She finds that she can easily implant thoughts into Kirk's mind, even altering his memory of a recent Christmas-party encounter between the two of them. Adams appears, overpowers Noel, seizes the controls, increases the neutralizer's intensity, and proceeds to convince Kirk that he has been madly in love with Noel for years. Kirk and Noel are then confined to quarters. On Kirk's orders, Noel enters the facility's physical plant through a ventilation duct, and interrupts Kirk's next neutralizer session by shutting off power to the entire complex. Freed from the neutralizer, Kirk attacks Adams, leaving him alone and unconscious in the treatment room. A guard discovers Noel's sabotage, they fight and she defeats him with an athletic kick that sends him hurtling into the electric circuitry, killing him. With the force field now off, Spock beams down to the planet, disables the force field, and restores power to the colony. This reactivates the neural neutralizer, which empties Adams' mind completely, killing him. Back on the Enterprise, Kirk is informed that van Gelder has destroyed the neural neutralizer. McCoy is surprised that loneliness could be lethal, but Kirk, after his experience, is not. Production The episode's title was taken from William Shakespeare's Macbeth. Macbeth is planning to murder the King of Scotland, and sees a dagger that he attempts to grasp, but it's only a hallucination. Playing mentally disturbed Van Gelder took a toll on the actor Morgan Woodward. Reportedly when he finished filming the episode he went home and took a rest for four days. Reception In 2010, SciFiNow ranked this the eighth best episode of the original series. Zack Handlen of The A.V. Club gave the episode a "B" rating, noting that the episode had "a handful of excellent moments (the mind-meld, that damn booth) that don't fit as well as they should". Handlen noted Kirk and Noel's relationship as the plot's "weakest element", and that Adams did not make a compelling villain. On the other hand, he felt that Nimoy made Spock's mind meld sequence "fairly effective". The booth and its effect on Adams were also cited as memorable moments in the episode. Legacy and