In this episode, evil children with magical powers mess with Captain Kirk's mind. In the scene below, Kirk is going crazy with groundless fears.

Spock drags him off the bridge and onto the lift, where they can be alone, away from their enemies. Frantic, irrational, Kirk breaks away from his grasp and vocalizes his distressed thoughts.

"I'm alone. Alone!" Jim cries, completely distraught (thus revealing his deepest fear).

Spock reaches out to grasp Jim's arm, and Jim turns and embraces him, desperately.

"Jim." Spock says, tenderly, as if to say, "Don't be silly. You will never be alone while I live."

Spock accepts Jim's embrace, and comforts and calms Kirk with a single syllable.

Amazed, Jim looks deeply into Spock's eyes, believes, and realizes his fear of being alone is completely ridiculous. He comes to his senses, and regains his confidence.

With renewed faith in each other, the two set off to confront the crisis - together.