One of the "unknown people" is shot while atop a dam near Silsby, Texas. Superman catches him before he falls into water and takes him to the Silsby hospital. Superman, in his Clark Kent identity, assists a doctor who operates on the creature. The doctor discovers his patient has all the organs and internal body structure as humans. Meanwhile, the Luke Benson-led mob tries to kill the other visitor from the center of the Earth. That creature escapes, later bringing up more of his people along with a weapon. Superman races to defuse an explosive situation.

[Episode 25 and 26 together were originally the movie "Superman and the Mole-Men" (1951). Information from http://fandom.wikia.com/:

"Superman and the Mole Men is a 1951 black and white film which later aired as two episodes of the Adventures of Superman TV series called "The Unknown People."

It was the first theatrical feature film based on the Superman characters (although two live action Superman films had already been shown in cinemas, they appeared in a serial format). With an original screenplay by "Richard Fielding" (a pseudonym for Robert Maxwell & Whitney Ellsworth), it was shot in 12 days on a studio back lot. It served as a trial run for the syndicated TV series Adventures of Superman, with George Reeves and Phyllis Coates reprising their film roles as Superman and Lois Lane, respectively."]

Clark Kent and Lois Lane travel to Silsby, Texas, site of the deepest well ever drilled. But when they arrive, the well is being shut down and the oil company manager present isn't saying why. Meanwhile, two short beings with large heads and furry hands come up from the well to explore. Luke Benson leads a mob of townspeople wanting to kill the "unknown people." Despite Superman's efforts to calm things down, the mob has tracked the two creatures to the top of a dam, trying to kill them. What the mob doesn't know is the creatures cause things they touch to glow in the dark -- and may be radioactive.

[Episode 25 and 26 together were originally the movie "Superman and the Mole-Men" (1951). Information from http://fandom.wikia.com/:

"Superman and the Mole Men is a 1951 black and white film which later aired as two episodes of the Adventures of Superman TV series called "The Unknown People."

It was the first theatrical feature film based on the Superman characters (although two live action Superman films had already been shown in cinemas, they appeared in a serial format). With an original screenplay by "Richard Fielding" (a pseudonym for Robert Maxwell & Whitney Ellsworth), it was shot in 12 days on a studio back lot. It served as a trial run for the syndicated TV series Adventures of Superman, with George Reeves and Phyllis Coates reprising their film roles as Superman and Lois Lane, respectively."]

The police are on the lookout for the Inventor of a robot, they believe the inventor is behind a crime wave instigated by the missing robot. Clark and his fellow reporters search for the truth.

When Jimmy goes to the docks to interview a actress who is arriving in port, he ends up being kidnapped by crooks who are attempting to smuggle something valuable into the country. Superman must step in to help.

Lois heads to a auction that has South American relics up for bid, while on the way she is approached by a man who requests that she purchase a Inca tapestry for him. Later the man is found dead and the tapestry is stolen from her. Clark and Jimmy become involved in the search for the murderer and the tapestry.

A psychic who operates a wax museum predicts the death of people with startling accuracy. Clark becomes determined to discover what is behind her erie predictions. 

Clark becomes fearful that his secret identity will be exposed when his apartment is broken into and his Superman uniform is stolen from it's hidden compartment. He attempts to discover who the thief is.

A sea monster and a deadly fog force residents to abandon their small village, when Lois visits a old friend, her and Clark become embroiled in the mystery.

Superman is determined to expose the crooked dealings of a wrestling organization who's fighters use a strange incapacitating technique.

A scientist uses a version of truth serum to cause employee's of the Daily Planet to do his bidding with no memory of what they did, afterwords. All to discover the secret identity of Superman.

A elderly coal miner's mine is tagged as too dangerous to prospect in by a mine inspector. Lois becomes trapped in the mine with him when they both ignore multiple warnings.

When three witnesses are due to testify against a criminal at a Congressional Crime Commission hearing, the crooks steal a machine that a inventor created to help people in order to stop the witnesses permanently.

A little girl accidentally receives information about valuable printing plates that were stolen from the Bank of France. The thieves track her down and Superman helps.

Lois decides to vacation on the Canadian border and runs into trouble when she is kidnapped by two gunmen.

A trained monkey is used to steal a secret formula that is to be used as a defense against atomic warfare.

Jor-El sends his infant son to Earth in a rocket just as the planet explodes. The rocket is found by the Kents, and they get the infant out before the craft explodes. Years later, Clark Kent is aware of his powers and moves to Metropolis.