The Keys of Marinus (S01E26)

S01E01 An Unearthly Child S01E01 Holiday Knights S01E02 The Cave of Skulls S01E02 Sins of the Father S01E03 The Forest of Fear S01E03 Cold Comfort S01E04 The Firemaker S01E04 Never Fear S01E05 The Dead Planet S01E05 You Scratch My Back S01E06 The Survivors S01E06 Double Talk S01E07 The Escape S01E07 Joker's Millions S01E08 The Ambush S01E08 Growing Pains S01E09 The Expedition S01E09 Mean Seasons S01E10 The Demon Within S01E10 The Ordeal S01E11 Over the Edge S01E11 The Rescue S01E12 Torch Song S01E12 The Edge of Destruction S01E13 Love is a Croc S01E13 The Brink of Disaster S01E14 The Roof of the World S01E15 The Singing Sands S01E16 Five Hundred Eyes S01E17 The Wall of Lies S01E18 Rider from Shang Tu S01E19 Mighty Kublai Khan S01E20 Assassin at Peking S01E21 The Sea of Death S01E22 The Velvet Web S01E23 The Screaming Jungle S01E24 The Snows of Terror S01E25 Sentence of Death S01E26 The Keys of Marinus S01E27 The Temple of Evil S01E28 The Warriors of Death S01E29 The Bride of Sacrifice S01E30 The Day of Darkness S01E31 Strangers in Space S01E32 The Unwilling Warriors S01E33 Hidden Danger S01E34 A Race Against Death S01E35 Kidnap S01E36 A Desperate Venture S01E37 A Land of Fear S01E38 Guests of Madame Guillotine S01E39 A Change of Identity S01E40 The Tyrant of France S01E41 A Bargain of Necessity S01E42 Prisoners of Conciergerie