PLAYED BY: James Gregory
SPECIES: Human Male

Director of the Tantalus V Penal Colony, Dr. Adams revolutionized mental hospitals making them less like cages and more like resort colonies. While working on Tantalus Colony, Adams developed a neural neutralizer that drained a person's thoughts and replaced them with whatever suggestions he wished to put there. When his colleage, Dr. Simon van Gelder, protested what Adams was doing, he subjected him to the neutralizing beam as a test subject, suggesting that van Gelder feel extreme pain should he try to remember what Adams had done to him. When Captain Kirk and Dr. Helen Noel visited Tantalus Colony, Adams subjected Kirk to the beam as well as a test subject. During a treatment session, the power was suddenly disrupted. When Adams went to investigate, Kirk knocked him unconscious and left him in the room alone. When the power returned, Adams was subjected to the beam at high intensity without anyone around to suggest anything to him. As a result, Adams died from loneliness.

PLAYED BY: Marianna Hill
SPECIES: Human Female

Psychology major serving aboard the U.S.S. Enterprise, Noel had met Captain Kirk at the science lab's Christmas party. Accompanying him to Tantalus V, Noel, along with Kirk, were held captive by Dr. Adams. While Kirk was being subjected to the neural neutralizer, Noel was able to crawl through the air conditioning ducts and reach the power control room where she was able to interrupt the security force-field surrounding the colony, allowing Mr. Spock and security team to beam down and assist.

PLAYED BY: Sussane Wasson
SPECIES: Human Female

Lethe came to Tantalus V as a patient, but following a treatment under the neural neutralizer, she became a therapist there, where she "loved her work."

PLAYED BY: Eliezer Behar
SPECIES: Human Male

One of the members of the Tantalus V staff, Dr. Eli was also one of the operators of the neural neutralizer, suggesting to one patient that he forget all that he had heard and to feel terrible pain should he try to remember anything. Eli was knocked unconscious by Captain Kirk when he escaped from the treatment room.

PLAYED BY: Anthony Larry Paul
SPECIES: Human Male

Transporter operator aboard the U.S.S. Enterprise, Berkeley mistakenly tried to beam down cargo to Tantalus V with their security screen up. After Captain Kirk corrected his mistake, he suggested that Berkeley brush up on penal colony procedures.