The Naked Time ()
A strange alien substance causes the crew to act out their deepest inhibitions, while the ship plummets out of orbit.
The USS Enterprise, under the command of Captain Kirk, arrives at the dying planet Psi 2000. Their mission is to observe and document the planet’s breakup and retrieve a research team stationed on the planet. Mr. Spock and Lt Joe Tormolen beam down and find the researchers’ life support system shut down and the team frozen to death. One fully clothed in a shower, one seated at a control console as if nothing was wrong, and one who was strangled. Tormolen removes his environmental suit glove to scratch his nose and comes into contact with a strange red liquid. The landing party is beamed back to the ship and examined by Chief Medical Officer Dr. McCoy. McCoy finds no medical issues with them and allows them to return to duty.
While having lunch, Tormolen begins to act irrationally, expressing hostility towards other crew members and threatening Lieutenants Sulu and Riley with a knife before turning it on himself. His wound is not life-threatening, but he dies after successful surgery in sickbay, to McCoy’s bewilderment.
Both Sulu and Riley also begin to behave irrationally. Sulu runs about with a sword, like a swashbuckler from the Three Musketeers. At the same time, Riley revels in his Irish ancestry, locks himself in the engineering section, and proclaims himself captain of the Enterprise. Those whose skin they have touched follow suit, and the infection quickly spreads through the crew. As they abandon their posts, the ship’s orbit destabilizes, and it falls into the planet’s erratic gravity well. As the Enterprise enters the upper atmosphere, the hull begins to heat.
Chief Engineer Scott regains control of engineering from Riley, but Riley has shut down the engines. It will be impossible to restart them by standard procedures before the Enterprise crashes into the planet.
Spock becomes infected when Nurse Chapel takes his hands and confesses her love for him. Spock struggles to contain his emotions and infects Captain James T. Kirk when he tries to help. McCoy studies blood samples from his patients and water from Psi 2000 and finds that the water possesses a previously undetected complex chain of molecules. This compound affects humanoids like alcohol, depressing the centers of judgment and self-control, and is transmitted by touch. He develops a serum to reverse the effects, administering the initial doses to the command crew to allow them to bring the ship back under control.
Kirk orders Scott to make a full-power restart of the warp engines. This dangerous process mixes matter and antimatter in a cold state to create a controlled implosion and drive the ship away from the planet. This is suggested by a theory postulating a relationship between time and antimatter, but it has never been attempted. The restart is successful, propelling the Enterprise at impossible speed away from the planet into a space-time warp that sends the ship back 71 hours in time. Spock comments that they now know a way to travel back through time. Kirk’s response is, “We may risk it someday, Mr. Spock.”