07/01/1961      Hot Snow (Dr. David Keel)

A package containing heroin is mistakenly delivered to the office of Doctor David Keel, and is unwittingly received by Keel’s fiancée, Peggy. But when the drug-dealer, Ronnie Vance, discovers the error, Peggy is murdered, and the police are unable to solve the case. Keel vows to avenge Peggy’s death, and uncovers the address of the doctor's office that should have received the drugs. Here he encounters a mysterious spy named John Steed; the two team up and set a trap for Vance, but the drug-dealer manages to escape just as the police close in on him…

14/01/1961      Brought to Book (Dr. David Keel)

In order to bring Ronnie Vance to justice, Steed convinces Doctor Keel to infiltrate the drug-dealer‘s gang while he joins that of a rival. Steed then arranges for a police raid, in order to convince Vance that Keel is crooked. Keel discovers that Vance and his brother are to be murdered by a member of the rival gang, but when he tells Steed, it leads Vance to realise that there are traitors in both gangs. He sends one of his thugs, Spicer, to kill Steed, but the heavy is captured and held captive by Keel, who threatens him with a deadly injection from a hypodermic needle. Unknown to Spicer, Keel is bluffing, and when the police arrive, he confesses to the murder of Keel's fiancée Peggy. Pleased with how they have worked together on the case, Steed enlists Keel as his permanent partner.

21/01/1961      Square Root of Evil (Dr. David Keel)

Steed is informed by ‘Five’, a colleague of his boss, ‘One-Ten’, that a forger, Riordan, is about to be released from prison, prior to starting work for an organisation that plans to flood the country with forged bank notes. While the forger is taken to a safe-house, Steed takes his place and infiltrates the organisation, gaining the trust of the leader, Hooper. But Hooper's second-in-command, the Cardinal, is suspicious of Steed and has him closely watched. Once he has uncovered their plans, Steed feigns a broken arm suffered while loading a truck, enabling him to reach Doctor Keel and inform him of the plot. After Keel returns with Steed a fight breaks out, and the police are then called in to arrest the villains.

28/01/1961      Nightmare (Dr. David Keel)

One of Doctor Keel’s patients, Faith Braintree, calls him in a panic - her husband, an eminent scientist working on a top secret project, has disappeared. Keel decides to help, but is mistaken for the woman's husband, and kidnapped. He manages to escape, and informs Steed, who convinces him to impersonate the scientist. Once again Keel is kidnapped, but when he attempts to escape again, he is shot in the chest and taken to a hospital for minor surgery. When the anaesthetist, an accomplice of the kidnappers, tries to kill Keel, Steed arrives just in time to save Keel's life. The scientist then reappears, apparently suffering from temporary amnesia caused by overworking.

04/02/1961      Crescent Moon (Dr. David Keel)

Carmelite Mendoza, daughter of General Mendoza, is kidnapped from her home in the Caribbean. Suspecting political motivations, Steed and Doctor Keel investigate the family, and later see the retainer, Vasco, killing the kidnapper and abducting the girl himself. Steed tracks Vasco down and forces him to reveal where Carmelite is located. But when he attempts to rescue her, Steed is attacked by Señor Paul, the man behind the abduction, who reveals that although he co-ordinated the original kidnapping, he was actually acting on the instructions of General Mendoza, who, suspecting that his wife and an accomplice were planning to murder him for his fortune, faked his own death and left for London, and then arranged for his daughter to be brought to safety too.

11/02/1961      Girl on the Trapeze (Dr. David Keel)

A girl reportedly jumps to her death in the waters of the Thames. But when Doctor Keel pulls a different girl from the water, her dying words are “Danilov”, the name of the girl who supposedly jumped. Suspecting foul play, Keel follows the trail to a visiting circus from Radek, where he meets Vera, a trapeze girl who is looking after an injured girl whose face is heavily bandaged. Before he can question the girl, Keel and his assistant Carol are captured by Zibbo the clown, who informs them that the girl is Anna Danilov; she is to be used to blackmail her father, Professor Danilov, a scientist who has defected to the west, into returning to Radek. Keel is told that unless he informs the police that he was mistaken about the girl, Carol will be shot. But although Keel does as instructed, the police are still suspicious. Keel returns and rescues Anna, while the police arrive and close the circus down

18/02/1961      Diamond Cut Diamond (Dr. David Keel)

Steed is instructed by One-Ten to pose as an airline steward believed to be a member of an illicit diamond smuggling ring, and who recently committed suicide. After taking up residence in his home at Heathrow, Steed meets Fiona Charles, a nurse with connections to Globe Airlines; following a successful flight to New York a party is thrown, and Steed subsequently returns home drunk. However, the next morning he awakes to find that he is now accused of killing a girl in a hit-and-run car accident that supposedly happened during the night. Doctor Keel is able to carry out blood and urine tests to determine that Steed was heavily drugged, and therefore was unable to have driven a car at the time. Absolved of the crime, Steed is then requested by Fiona to deliver a package to New York. Returning home, he is confronted by Fiona and her employer, Doctor Collard; having decided that his usefulness is over, the two smugglers intend to kill him and make it look like a suicide. But just before their plan can be put into practice, Keel arrives with the police.

25/02/1961      The Radioactive Man (Dr. David Keel)

At an atomic research facility, the caretaker steals a capsule of radioactive material and then makes off. Doctor Keel learns that not only will the stolen isotope kill the thief, but also anyone else who comes into close proximity with it within thirty-six hours of contact. The man mistakenly believes that he is being pursued by the police because of a forged passport, and goes into hiding. When his girlfriend arranges for him to meet someone who will get him safely out of the country, it transpires that the man really intends to kill him for the fee. After Steed provides Keel with a lead, the doctor is able to uncover the thief's whereabouts from his girlfriend. Keel and a doctor from the research facility use a Geiger counter to track the thief and the isotope down in time.

04/03/1961      Ashes of Roses (Dr. David Keel)

While investigating a spate of arson cases, Steed arranges for Doctor Keel's assistant Carol to have some time off for a hairdressing appointment. But when Carol asks questions at the salon run by Olive and Jacques Beronne, she is nearly killed when the hairdryer she is using explodes. This booby-trap was actually intended for Denise, the hairdressers’ assistant, and is the proof Steed needs that the salon's owners are involved with Mendelssohn, a known arsonist, in a scam to destroy the nearly-bankrupt salon, in order to collect the insurance money. When Steed confronts Olive and Jacques, the latter confesses that the salon is to be burnt don that night. Meanwhile, Denise tells Carol that she suspects Mendelssohn of intended arson; the two head for the salon, but are saved from being burnt alive when Steed arrives and knocks Mendelssohn out just before he can light the fuse.

18/03/1961      Hunt the Man Down (Dr. David Keel)

Frank Preston is released from prison after serving a long prison sentence for robbery. He heads directly for his stolen loot, which he previously hid in a sewer, but before he is can get to it, he is confronted by thugs, who beat him up in an attempt to discover the location of the money. Doctor Keel treats Preston for his wounds, but the thugs then assume that Keel knows the whereabouts of the money and so kidnap his assistant Carol. After Preston escapes from hospital, he finds out that his wife, Stella, is involved with the thugs; he then returns to the hospital and forces Keel to help him retrieve the loot. When Preston and Keel arrive at the Sewer, the thugs corner them - luckily, they in turn have been followed by Steed and the police.

01/04/1961      Please Don't Feed the Animals (Dr. David Keel)

Felgate, a minor civil servant, suspiciously leaves a package in the reptile pit of a private zoo. Steed suspects him of passing secret information, and his investigations lead him to allow himself to be blackmailed by the owner of a Soho club. Steed soon finds himself instructed to leave a similar package at the private zoo. Meanwhile, Doctor Keel discovers that the packages are being collected by a monkey and taken to a girl at a refreshment kiosk, who subsequently turns out to be the leader of the blackmail ring.

15/04/1961      Dance with Death (Dr. David Keel)

When Elaine Bateman, the owner of a dancing school, is gassed, Doctor Keel revives her, and she insists that she is the victim of a murder attempt. Keel instigates the school and meets her partner Major Caswell and the school pianist, Anthony. Keel is forced to leave after an altercation with Price, a student who was in love with Elaine, but he accidentally leaves his scarf behind. Later on, Elaine is found strangled with Keel’s scarf, but Steed is able to vindicate his partner, instead suspecting Anthony, who had previously been accused of murdering his wife, who was electrocuted by a radio thrown into her bathtub. Steed attempts to track Anthony down, but finds that he has eloped with Valerie, a young woman whom Anthony met through the dance school, and who is in possession of a large cache of diamonds. Steed and Keel arrive just in time to prevent her murder, arrest Anthony, and return the jewels to Valerie’s mother.

29/04/1961      One for the Mortuary (Dr. David Keel)

Steed conceals a microdot containing information about a new medical formula on a conference invitation card, which he gives to Doctor Keel. Unaware of the information he is carrying, Keel travels to Geneva for the conference. While en route, he treats a young woman, Yvette; he then invites her to the conference, and gives her the invitation. When Keel is later arrested on a charge of murder, Steed locates Yvette, but discovers that the doctor who was intended to receive the information is allied with the thugs trying to steal it, and is also responsible for the murder. Steed has the doctor arrested, and then he and Keel return to England with the invitation card.

13/05/1961      The Springers (Dr. David Keel)

Steed is investigating the escape of several prisoners from prison, and sends in Doctor Keel to impersonate an inmate who is to be sprung soon. Steed follows the trail of clues to a finishing school for young women, and together with a young agent, Caroline, they infiltrate the premises. But while searching a room, Steed is captured and brought before Neame, the gang’s organiser. When Keel subsequently arrives, he is identified as an impostor and imprisoned as well. Steed and Keel face death, but Steed manages to outwit their captors and Neame is arrested.

27/05/1961      The Frighteners (Dr. David Keel)

Led by a man called the Deacon, ‘The Frighteners’ is an organisation that can be contracted to "massage patients”, by beating them up in order to persuade them to behave. Steed gives Doctor Keel a chance to see the organisation in action when a wealthy businessman, Sir Thomas Weller, pays to keep Jeremy de Willoughby away from his young daughter Marylin - the prospective groom is pursuing the rich man's daughter in order to pay off his dubious creditors. While Steed investigates de Willoughby, Keel goes after the Deacon. Weller is unable to frighten de Willoughby away from Marylin, and so Steed and Keel decide to form an ‘organisation’ of their own to frighten her away from de Willoughby.

10/06/1961      The Yellow Needle (Dr. David Keel)

Sir Wilberforce Lungi arrives in London in order to negotiate independence for his African nation. But when an attempt is made on the delegate’s life, Steed is called in to investigate. After Steed travels to Africa, he discovers that Jacquetta Brown, Sir Wilberforce’s assistant, is a member of an opposing group, but he is then captured. Steed escapes, and manages to warn Doctor Keel, who is an old friend of Lungi. An attempt by Jacquetta to replace Lungi's insulin with lethal yellow fever virus is thwarted by Keel, when he arrives in time to overpower her.

24/06/1961      Death on the Slipway (Dr. David Keel)

Steed poses as a metallurgist in order to enter the dockyard where a nuclear submarine is being built. Here he encounters an old nemesis, Kolchek, who blackmails the yard foreman into planting a bomb to kill Steed, so that he can obtain the plans to the craft. When Steed catches Liz Fleming, the foreman's lover, searching his room, he is able to learn about the bomb. He manages to find it, throwing it into the water just before it explodes.

08/07/1961      Double Danger (Dr. David Keel)

While treating a patient’s wounds, Doctor Keel discovers that he was a part of a recent diamond heist. Keel gets the man's partner to fetch a prescription from a hospital; but then his assistant Carol notices a cryptic entry on the prescription: ‘Phonus Equus’, which is Latin for ‘call Steed’ - Keel does just that, and informs his partner of the location of the diamonds. But when the man's partner returns to find that the injured man has died, he realises that Keel must have disclosed the location of the diamond's whereabouts, and so kidnaps Carol, threatening to kill her if unless Keel reveals the location to him. Keel is forced to reveal his information, but when the two of them arrive at the hiding place, they find Steed and the police waiting for them.

22/07/1961      Toy Trap (Dr. David Keel)

Bunty, a friend of Doctor Keel is worried about the disappearance of her roommate Chrissie. Asked to help, Keel investigates, and discovers that a prostitution ring is soliciting girls living in the hostel. When another girlfriend agrees to enter the prostitution ring, it allows Steed to uncover the prostitution ringleader - Mrs. McCabe, the hostel's landlady.

05/08/1961      The Tunnel of Fear (Dr. David Keel)

Top-secret information is apparently being leaked through a funhouse located in Southend. Meanwhile, Doctor Keel coincidentally treats Harry Black, a man recently escaped from prison who was injured while working in the funhouse. Steed takes a job at the funhouse, but he is exposed by the funhouse hypnotist, who knocks him out, and then attempts to extract information from him. When this ploy fails, Steed is imprisoned on the ‘Ghost Train’, where he discovers a machine that transmits coded information to Europe is being used by Wickham, the boss of the funfair. Doctor Keel arrives at the funhouse just in time to find Steed bluffing his way out of captivity with the use of an ‘exploding cigarette’.

19/08/1961      The Far Distant Dead (Dr. David Keel)

While en route to England, Doctor Keel stops off in Mexico City to help the victims of a recent cyclone. But when he meets a man with acute food poisoning, he discovers that the cooking oil flown in is actually hydraulic fluid. When Keel teams up with another doctor, Ampara Alverez Sandoval, in order to track down the origin of the oil, they find that the trail leads back to a financier called Zebrugge. Keel arrives in time to prevent Sandoval from exacting revenge against the financier for the death of the villagers.

02/09/1961      Kill the King (Dr. David Keel)

King Tenuphon is visiting London in order to sign an oil deal. Steed is assigned to protect him, as there has already one attempt on the King's life aboard his plane bound for London. Meanwhile, Major Harrington, a paid assassin rents the flat across from the hotel where the King is staying. Steed double-checks the area, but the landlady tells him nothing as her husband is under threat of death. A low-flying helicopter distracts the king’s attention, Steed immediately suspects foul play; he hurls himself at Tenuphon, and the Major instead kills Prince Serrakit, the king’s advisor. Tenuphon’s bodyguard Tuke is then able to shoot the Major.

09/12/1961      Dead of Winter (Dr. David Keel)

After the frozen body of Gerhart Schnieder, a wanted Nazi criminal, is discovered amongst a beef shipment, Steed and Doctor Keel follow the trail to a Nazi revivalist group called Phoenix. After discovering that Doctor Kruezer, one of the members of the group, has perfected a method of cryogenics, Steed suggests that Keel joins the organisation. Here, Keel finds that the assumed dead man is very much alive; but Keel is soon discovered and lined up as the next deep-freeze experiment. Just in time, Steed arrives and rescues Keel, who comes away from the ordeal with nothing worse than a cold.

16/12/1961      The Deadly Air (Dr. David Keel)

After the testing of a vaccine goes horribly wrong, Steed and Doctor Keel investigate, and discover that Heneger, one of the scientists involved, is attempting to sabotage the project. But while interrogating the suspect, they learn that another scientist called Doctor Craxton is really behind the plan. Craxton locks Steed in a room booby-trapped with a vial of lethal virus. Keel believes that Steed is infected, but then learns that Truscott, the project director, replaced the vials of virus with vials of water by as a security precaution. The security guards arrest Craxton.

23/12/1961      A Change of Bait (Dr. David Keel)

When Archie an elderly man who suffers from heart disease, tries to sell a consignment of bananas, he is caught up in an insurance scam by a crook named Lemuel Potts, who attempts to hold up the transaction long enough for the fruit to go rotten, enabling his accomplice, Bartsow, to claim on the insurance. But Steed intervenes, and the deal goes through. Potts then attempts to collect on another insurance policy on by burning down an antique shop; however, Steed and Keel arrive and put the fire out, and then photograph Potts when he attempts to relight the fire. Steed tricks Potts into revealing his accomplice, Barlow. As the villains are arrested, Steed gets Potts to give him a cheque, which he uses to pay Archie for the bananas, much to the amusement of Doctor Keel.

30/12/1961      Dragonsfield (Dr. David Keel)

After a scientist is badly exposed to radiation, Steed is sent to investigate a spacecraft facility that is working on making a special material to shield astronauts from radiation. Working alone, Steed discovers that the security officer, Saunders, has warned Doctor Alford, one of the team of scientists, about fraternising with his assistant Susan Summers. After rescuing Alford from an unknown assailant, Steed is almost killed when someone tampers with the equipment that he has volunteered to test. He then learns that Saunders has cracked the saboteurs’ code, and has arranged a meeting at the local pub; but Steed arrives too late, and finds that Saunders has been captured by two gunmen. Steed tracks them down to a disused flour mill, rescues Saunders, and forces one of the gunmen to reveal the identity of the saboteur: Susan Summers. Steed rushes back to the research centre, just in time to stop Susan from killing another member of the team.