The sixteenth season of British science fiction television series
Doctor Who, known collectively as The Key to Time, began on 2
September 1978 with The Ribos Operation, and ended with The Armageddon
Factor. The arc was originally conceived by producer Graham Williams,
who had proposed it as part of his application for the producer's job
in 1976. The name refers to the powerful artefact, the segments of
which are what the Fourth Doctor and his companions, Romana and K9,
search for during the season.A figure calling himself the White
Guardian commissions the Doctor and K9, assisted by a new companion,
the Time Lady Romana, to find the six segments of the Key to Time, a
cosmic artifact resembling a perfect cube that maintains the
equilibrium of the universe. Since it is too powerful for any single
being to possess, it has been split into six different segments and
scattered across space and time, disguised by the raw elemental power
within them into any shape or size. However, since the forces
balancing the universe are so upset, the White Guardian needs to
recover the segments of the Key to stop the universe so that he can
restore the balance. The White Guardian also warns the Doctor of the
Black Guardian, who also wishes to obtain the Key to Time for his own
purposes. In the final episode, the Black Guardian, disguised as the
White Guardian, attempts to take the Key from the Doctor. However, the
Doctor sees through the figure's charade and orders the segments of
the Key to Time to once again become scattered across all of time and
space, bar the sixth, which he reinstates as Princess Astra.
Afterward, the Doctor decides to install a device called a randomiser
into the TARDIS' navigation system for a period of time to make his
following voyages unpredictable to evade the Black Guardian.Tom Baker
continued his role as The Fourth Doctor, and saw the introduction of
Romana played by Mary Tamm. This season was the only one to feature
Tamm as the first incarnation of Romana, as the second incarnation,
played by Lalla Ward, began her run in the first serial of the next
season (Destiny of the Daleks). Doctor Who (season 16) Biography, NetWorth, Height, Age, Weight, Family, Married, Son, Daughter