A storybook is open and we begin with a game of cricket. The bowler bowls, the batsman bats, and the ball ends up in the bushes. The first sinister event occurs as the ball is replaced by another one. It looks the same and bowls the same, except it explodes - killing the unfortunate batsman. Colonel "Hawke-English", the deceased batsman, was investigating the activities of a mad scientist called Schnipps who is building a rocket to destroy London.

A new man is appointed to carry on where the Colonel left off. Looking suspiciously like our friend No. 6, he finds himself on the same cricket ground and about to bat. The bowler bowls, the batsman bats, and the ball ends up in the bushes. Again, the ball is replaced with a deadly doppelganger but No.6 manages to throw the ball away before the explosion. Checking the bushes he finds a message written on a handkerchief : "Let's meet again...at your local pub".

There, another message under his pint glass reads "You have just been poisoned". After drinking various strong drinks, he manages to, er, cleanse his system. Another note waits for him, directing him to the "Turkish baths" where he appears, dressed as Sherlock Holmes. He is then locked inside his steamer but manages to break out just as he was beginning to suffocate. He is then directed to a fairground, takes part in a boxing match, is led to the "tunnel of love" and to a ride, now in pursuit of a girl clad in white. Following her in his car, he hears her voice on his radio and she manages to make his vehicle spin with a movement of her finger.

They end up in a deserted village named "Witchwood" and, taunting him through a loudspeaker system, the girl reveals her name as "Death". No.6 goes through the butcher's, baker's and candlestick maker's shops, each with a built-in death trap. He manages to evade death each time and commandeers a bulldozer for protection but the girl blows up the machine using a rocket launcher. Hidden in a manhole, the prisoner is still alive and clings onto the helicopter with which the girl is leaving.

Following her into a network of underground tunnels, he finds a military establishment in the style of a Napoleonic encampment (the operative word here being "camp"), with the soldiers all dressed as Napoleon. He knocks out one of the soldiers and sabotages the weapons he sees around him. Dr Schnipps, father of the girl whose real name is Sonia and also dressed as Napoleon, inspects his soldiers, telling them he is about to fulfil his dream and destroy London. They notice that one of their colleagues is missing and go to look for him. They fight with No.6 and are finally defeated when their sabotaged rifles backfire. Ascending to the top of the lighthouse, No. 6 is captured by Sonia and tied to a chair.

It's revealed that the lighthouse is actually the rocket, shortly to launch and with him as the passenger. As Schnipps and Sonia are busy packing their files, No.6 manages to free himself. He resets the rocket's controls and escapes by climbing down the outside of the lighthouse/rocket. As he reaches the motorboat, Sonia and Schnipps appear at the door and throw mortar bombs at him but these are the ones he's sabotaged and the handles explode in their hands. As he skims away, the rocket explodes.

"And that is how I saved London from the mad scientist", says No. 6. He's been reading the story to two Village children. In the "Green Dome", Schnipps is revealed as No.2 with Sonia as his assistant. They have been listening to the whole story, hoping that the Prisoner would drop his guard with children around and reveal his secrets. As ever, he disappoints and as he leaves he turns to the monitoring camera and says: "Goodnight children...everywhere".