At Marseilles airport, Steed and Cathy find the courier they were due to meet dead. His sample of new liquid rocket fuel has been taken. Facing an array of enemy agents, the duo must recover the flask of Propellant 23.

Borb, the president of the Balkan Republic, is visiting London to sign a military deal. His private secretary is killed by a masked wrestler, the Decapod. Steed is assigned to augment the president's bodyguards, but the wrestler continues to kill those close to Borb.

Shareholders in Anderson's, a small-arms manufacturers, are being killed one by one whilst a tycoon plans a take-over. Rifles and other weapons, possibly manufactured by Anderson's, are being smuggled into Africa. Cathy Gale joins the board with a 20 per cent share in order to investigate.

A film star's stand-in is murdered, and microfilm of North American early warning systems has been stolen. The film star, despite an aversion to travelling by sea, proceeds to Montreal on a luxury liner. In an attempt to find the mocrofilm Dr King is assigned as her personal doctor, and Steed goes under cover as a steward.

Steed is trying to infiltrate a group of assassins currently based in the South of France. He robs the leader of some jewellery in order to impress him, then waits for them in the local club. It just so happens that Venus Smith is singing there.

The owner of a stamp shop is murdered when excitedly talking on the phone to a contact about the rare Mauritius Penny that has turned up on a list. Cathy Gale applies for a job in the shop, and she and Steed witness another murder in an auction room.

A man involved in a car crash is found to have fifty thousand pounds worth of diamonds in his stomach. Steed investigates the man's joke shop, Big Laugh, and then the offices of multi-millionaire Litoff. The burial of one of Litoff's Great Danes is not quite what it seems.

Steed's department is guarding M. Roland, A UN negotiator in London for important talks, but cannot prevent an assassination attempt. Indeed, it seems that one of Steed's colleagues is selling secrets - and Steed finds that even he is under suspicion.

Illegal diamonds are swamping the market. The wife of a diamond merchant is murdered. Time for Steed and Gathy Gale to feign marriage.

Secrets are finding their way from HMS Zebra, a naval base, to the enemy, rendering the Navy's missile-tracking equipment useless. Steed and Mrs. Gale investigate, and find their attention drawn to the local sweet shop.

Plato, the most advanced computer in the world, which could be used to target intercepting missiles, keeps breaking down. The body of a professor on the team is found within.

A British courier is attacked in Jamaica, and he protects the contents of his diplomatic bag at the expense of his life. But why? The case only contains mundane documents.

A plane crashes in Ireland in suspicious circumstances, and the bodies are taken to the nearby St. Mary's Convent . Steed calls in Dr. King to check up on the circumstances of death, while he samples Irish hospitality and bad deeds at Shamrock Airport.

Steed wants Mrs. Gale to impersonate Hilda Stern, a recently arrested assassin about to be used by the trans-national crime syndicate Intercrime. Things go swimmingly, until the real Hilda Stern breaks out of Holloway and confronts the imposter.

Marling Ceramics, run by Cathy's friends, Richard and Allan Marling, claim to be on the verge of creating an unbreakable china. However, when Steed arrives to investigate, a body is discovered in a tank of clay.

Classified information is finding its way into the wrong hands and Steed feels sure that this has something to do with the death of the magician's assistant at the club where Venus Smith is working. Steed investigates the lethal vanishing cabinet.

Steed is entrusted with the safe-keeping of a new fuel formula when its inventor is found in a coma. The scientist had been involved in a black magic circle which leads Steed and Cathy into the world of hexes and magic powers.

A burglar steals two gold-plated eggs from Dr Ashe, not knowing that they contain a deadly virus. The man quickly falls ill, but refuses to indicate where the case containing the eggs is buried.

Steed, investigating the suicide of a University tutor, discovers that the man seems to have shot himself with a gun with a silencer attached. Venus is sent a tub of acid 'face-cream', and there is another mysterious suicide.

Astonomer Professor Richter believes that the sun's stellar companion, a white dwarf, is returning to the solar system. If it does, that's the end of everything. So why on Earth would anybody want to murder him now?

Venus has her camera and films stolen whilst taking pictures in a fun fair. One film is missed, however, and when developed a face can be seen in the Hall of Mirrors - that of Trevelyan, the cypher clerk who has committed suicide. But Venus's photograph was taken after the man's death.

The Mafia aren't about to let Steed get in the way of their lucrative drug-smuggling operation between Britain and North America, and arrange for him to be assassinated. Steed survives, and tracks his intended killer to a circus, where some of the clowns prove to be anything but figures of fun.

A holiday for Steed in Greece is, of course, no straightforward affair. A deep-sea diver dies in mysterious circumstances, whilst bathyscope experiments are taking place on the yacht where Venus is singing.

What should have been a quiet weekend at the home of an old friend soon turns into a thick web of treachery and scheming, which throws Cathy into the world of shipbuilding, cross-company romance, mysterious 'accidents' and misguided nationalism.