The fourth planet of Star System 892 os a Class-M planet that bears many similarities to Earth. Planet IV`s atmospheric composition, water-to-land ratio, equatorial diameter, and density are, bizarrely, identical to Earth`s.  In an extraordinary example of Hodgkin`s Law of Parallel Planet Development, the inhabitants have also developed a culture which closely parallels that of Earth; the planet has reached the technological level of Earth`s 20th century and the inhabitants have built industrialized cities, complete with familiar technologies such as radio and television. The cities have communication capabilities, excellent road systems, power transportation, and the pollution that accompanies it.

Society on Planet IV is fascist, and is structurally very similar to the Roman culture which flourished on Earth for over 1,000 years. It is an ordered world, very conservative and free from chaos. It is ruled by emperors who can trace their lineage back 2,000 years, and the society has developed to reflect time honoured strengths and virtues. There has not been a war on Planet IV for over 400 years, but the culture on the planet ignores human rights in a way which became unacceptable on Earth. Slavery and gladiatorial combat are instituitionalized.

Slaves have duties that range from being gladiator fighters for the evening`s broadcast to being personal slaves whose only responsibility is to be beautiful and to pleasure their masters. They are dressed in gray uniforms, battle gear or revealing attire.

They are not free to come and go as they please, and are nor treated equally under the law, despite having rebelled against their rulers years ago; the rebellions were suppressed. However, with each new century the slaves acquired additional legal entitlements, and now enjoy the right to medicine and government payments in old age.

Many slaves are  content with these modest entitlements, but others have formed a pacifist movement. They call themselves the `Children of the Son`, and preach a powerful message of love and brotherhood among all men. The authorities have tried to disrupt this movement and have succeeded in keeping the `message of the Son` from the slaves fro centuries. However, the Son`s teaching that all men are brothers and peace is the only way is too strong to remain suppressed forever.

The rebel slaves live a primitive existence in caves not far from the city. They live peacefully among themselves, but they are occasionally captured by the police and forced to fight in gruesome public displays of violence.

Rulers like Proconsul Claudius Marcus keep slaves and citizens alike from the philosophy of the Son. Using mass media and propaganda, he belittles the beliefs of those who follow the word of the Christ-like figure. The Proconsul is completely convinced that the Roman way of life is superior, and is unwilling to tolerate any alternative points of view. Consequently, the Children of the Son often find themselves fighting in the televised gladiatorial combats that are the mainstay of the population`s entertainment.

The television programming features regular broadcasts of fights in which barbarians and slaves battle to the death before a live audience in a show called `Name the Winner`. These shows are dependent on audience rating systems and advertising revenue.

The Federation becomes involved when the crew of the USS Enterprise attempts to retrieve a Federation citizen, Captain RM Merrick, who has joined the society of Planet IV as First Citizen Merrikus. Merrick was persuaded to stay by Proconsul Marcus, who is determined to protect his world from contamination by outsiders. Merrick is now the `lord of the games`, a calculating butcher with a cold demeanour. Those members of Merrick`s crew who refused to cooperate died at the hands of gladiators. Any deviation from the rules of the game, or from the tyrannical rule of Proconsul Marcus, results in an immediate death sentence.

When Captain Kirk eventually contacts Merrcik he appears to be completely happy with his new life. However, Kirk eventually pricks his conscience and Merrick sacrifices his own life while helping the Enterprise landing party to escape.