The Keys of Marinus
The Keys of Marinus is the fifth serial in the British science fiction television series "Doctor Who" , which was first broadcast on BBC1 in six weekly parts from 11 April to 16 May 1964 . 
<triplet> The Keys of Marinus <subj> Doctor Who <obj> part of the series <triplet> Doctor Who <subj> science fiction television <obj> genre <subj> BBC1 <obj> original broadcaster