A microfilm of North American early warning plans has been stolen and is believed to be somewhere in the luggage of a fading film star. Steed and Dr. King are assigned to retrieve it during a trip across the Atlantic on an ocean liner.

A British plane crashes under mysterious circumstances in Ireland. Steed leads take him to the Shamrock airport and a convent, while Dr. King performs autopsies are the dead passengers hoping to find a clue pointing to the wreck's cause.

While guarding a United Nations negotiator after an assassination attempt, Steed and a colleague fall under suspicion for selling state secrets.

The Home Office is mystified when a diplomatic courier dies defending a satchel full of mundane documents. Steed and Cathy follow a trail of clues from Jamaica to Chile to Argentina to solve the crime.

Steed and Cathy travel to Marseilles to pick up a flask of a secret new rocket fuel. When they arrive at the airport, they find the bottle gone and their contact dead. The pair battle foreign agents to regain the propellant.

One-Ten is convinced that the man is murdered while being interviewed on a live television show was the victim of a hired-killer called "The Teddy Bear." He concocts a plot to trap him using John Steed as bait and Cathy Gale as the woman who wants to hire an assassin to murder him.

The president of a Balkan Republic is menaced by a masked assassin. Although Steed is sent to augment the visiting dignitary's security detail, his bodyguards are murdered one by one.

The Home Office becomes concerned when gunrunning to Africa increases and the stockholders of a prominent British gun manufacturer are being murdered one by one. Cathy buys 20 percent of the company's stock to investigate their activities.

Steed is ordered to infiltrate a gang of assassins. His appointment with their leader is in a small jazz club where Venus Smith is singing.

A stamp collector is murdered after he discovers an extremely rare penny stamp being offered for sale on the open market. Cathy takes a job in the stamp collectors store to gather more information, but is unable to prevent a murder in an auction room.

Steed investigates when the autopsy of a automobile accident victim reveals 50,000 pounds worth of diamonds in his stomach.

Steed and Cathy investigate the death of diamond importer's wife and its connection to smuggled diamonds that are flooding the market.

Steed and Cathy investigate security leaks at a secret Navy base which renders its missile defense system useless. The trail leads to a sweet shop and the local pub with a very special dartboard.

A powerful computer used to target incoming missiles continually breaks down. When one of scientists who developed the machine is found dead inside it, Steed and Cathy are asked to investigate.

Cathy Gale impersonates a female assassin in order to get evidence needed to break up an international criminal syndicate. Before Cathy can complete her mission, the real murderess escapes from prison.

Steed is asked to guard a revolutionary new formula for fuel when its inventor is discovered in a coma. When he learns that the scientist was a member of a black magic cult, he and Cathy investigate.

Cathy's friends claim to have invented an unbreakable ceramic. Sinister forces want the formula for uses that have nothing to do with cups and saucers.

Steed traces stolen classified documents to a nightclub where Venus Smith is working as a magician's assistant.

A thief steals two gold-plated eggs from Dr. Ashe, not realizing they house a deadly virus. Even though the burglar becomes extremely ill, he refuses to reveal where he has hidden the eggs.

Steed investigates the alleged suicide of a college instructor and discovers that the weapon the man used to kill himself was a pistol with a silencer attached.

A famous astronomer predicts that the entry into the solar system of a small star will result in the destruction of the Earth. Steed and Cathy try to discover the connection, if any, between the astronomer's dire prediction and the threats on his life.

Venus Smith's camera and film are stolen at a fair. When Venus develops the one roll remaining in her possession she discovers she has taken a photograph of a man thought to have committed suicide days earlier.

Steed survives an attempt by the Mafia to assassinate him for interfering with their drug traffic and tracks the would-be killers to a smaller provincial circus.

While on holiday in Greece, Steed becomes involved in the investigation of a deep sea diver's mysterious death.

Cathy's quiet weekend visiting with a friend is ruined by treachery, scheming and mysterious accidents.

Steed suspects that the gymnasium Cathy is using to train a prize-fighter is actually the front for a gang of ambergris smugglers.