Enlightenment is the fifth serial of the 20th season of the British science fiction television series Doctor Who, which was originally broadcast in four twice-weekly parts on BBC1 from 1 to 9 March 1983. It was the 127th serial of the series, and was written by Barbara Clegg and directed by Fiona Cumming, making it the first serial to be both written and directed by women. In the serial, the alien time traveller the Fifth Doctor (Peter Davison) and his companions Tegan Jovanka (Janet Fielding) and Vislor Turlough (Mark Strickson) encounter a group of god-like immortals who are racing historical sailing vessels from Earth through space, crewed by humans they had plucked out of time, in an attempt to win the prize of enlightenment. Turlough is under the control of the Black Guardian (Valentine Dyall), but struggles with the Guardian's orders to kill the Doctor. Enlightenment is the third of three loosely connected serials where the Black Guardian attempts to compel Turlough to kill the Doctor. The serial's production was beset by problems caused by industrial action taken by electricians at the BBC during filming. It was eventually finished three months behind schedule, but the unavailability of several actors for new filming dates forced the production team to recast their parts at short notice. Enlightenment averaged 6.8 million viewers per episode on its first transmission and received generally positive reviews from critics. Plot Following interference from both the White and Black Guardians, the Fifth Doctor materialises the TARDIS in what appears to be the hold of an Edwardian yacht, though the Doctor senses something is amiss. The human crew have no idea how they got there nor where they are, but know they are taking part in a race. The Doctor and his companions, Tegan and Turlough, discover that the yacht and several other historical Earth ships are competing in a solar sail race through the Solar System. The ship's officers reveal themselves to be "Eternals", in contrast to the Doctor and the humans, whom they somewhat dismissively call "Ephemerals". The Eternals live in the "trackless wastes of eternity" and rely on Ephemerals for their thoughts and ideas. This race is being held by the Guardians and the prize is Enlightenment, the wisdom to know everything. The Doctor finds that the Eternals have made his TARDIS vanish, forcing him and his companions to stay until the race's conclusion. As the