The TARDIS materialises on an island in the middle of a sea of acid. The planet of Marinus has many inhabitants and many climates. The First Doctor, Susan, Ian and Barbara are sent on a quest to recover the four keys of Marinus. This will restore the Conscience of Marinus, a computer which maintains law and order. The TARDIS crew travel to two cities, a jungle, and an icy wasteland in search of the keys. However, they are pursued by the relentless Voord, who resemble amphibious ninjas. The Voord are subtle and they carry daggers! The Voord are extremely dangerous!

The Keys of Marinus

★★☆☆☆

TX: 11/04/1964 – 16/05/1964

Written by Terry Nation  Directed by John Gorrie

The TARDIS lands on the planet Marinus, on an island in the middle of a sea of acid. The TARDIS crew are tasked with recovering the four keys of Marinus which will restore the Conscience of Marinus, a computer which maintains law and order. However, the First Doctor, Susan, Ian and Barbara are pursued by the ninja-like Voord. The Voord are amphibious and they carry daggers! They are subtle and they can creep up behind you. The TARDIS crew travel to two cities, a jungle, and an icy wasteland in search of the keys. The Doctor even has to present evidence in court! Upon returning to Arbitan’s island with the keys, the time travellers are unaware that the Voord have taken over. Altos and Sabetha have been held prisoner by Yartek —Arbitan’s killer—and the four keys have been seized. The Doctor frees Altos and Sabetha and unmasks the Voord. Ian gives Yartek a false key found in the screaming jungle; when Yartek places the key in the Conscience, the machine explodes and he is killed along with the occupying Voord. The Doctor, Susan, Ian, and Barbara flee the tower with Altos and Sabetha before the growing blaze overtakes the ancient structure. Some elements of this story were reused for The Infinite Quest.