Ep 26. The Keys of Marinus (6)

"The Keys of Marinus" is the sixth episode of the first season of Doctor Who. The episode follows the Doctor, along with Barbara, Ian, and Susan, as they search for the six keys that will unlock a machine that can control minds. The four of them travel to the planet Marinus, where they encounter various dangers and obstacles as they try to retrieve the keys.

The episode begins with the TARDIS crew landing on Marinus and meeting a group of people known as the Arbitan. The Arbitan tells them of the machine called the Conscience of Marinus, which can control the thoughts of all the planet's inhabitants. However, the machine has been taken over by a man named Yartek and his group of Voords, who seek to use it for their own purposes. The only way to stop them is to use the machine's six keys to reset it.

The Arbitan had previously sent out six teams to retrieve the keys, but they all failed and were killed. He now turns to the Doctor and his friends for help. The TARDIS crew agrees to search for the keys, and the Arbitan gives them a device called a time-rotor, which will take them to each of the key's locations.

The first key is located in a walled city, where the inhabitants believe that the outside world is toxic. The crew must convince them otherwise and retrieve the key from a hidden vault. The second key is located in a jungle, where they must navigate through dangerous plants and fend off angry natives to retrieve it.

The third key is located in a snow-covered mountain range, where they must escape from an imprisoned mad scientist and his deadly experiments. The fourth key is located in an underwater city, where they must outsmart the Voords and evade the deadly sea creatures that live there.

The fifth key is located in a desert, where they must navigate through a deadly sandstorm and avoid being captured by the damp desert dwellers. The final key is located in a city made of glass, where they must navigate through a maze-like structure to retrieve it.

Once all six keys are retrieved, the TARDIS crew returns to the Arbitan, only to find that Yartek and the Voords have attacked and taken over the Arbitan's headquarters. The crew must battle the Voords and use the keys to reset the Conscience of Marinus, finally defeating Yartek and restoring peace to the planet.

Overall, "The Keys of Marinus" is an exciting adventure story that showcases the TARDIS crew's resourcefulness and bravery as they overcome a variety of obstacles and challenges in their quest to save a planet from tyranny. It's a classic episode that embodies the spirit and enduring popularity of Doctor Who.