Dr. Who: Fury from the Deep

Fury from the Deep is the missing sixth serial of the fifth season of Doctor Who, which was first broadcast in six weekly parts from March to April 1968. Starring Patrick Troughton as the Doctor, the story concerns a colony of sentient, parasitic seaweed, last seen in the eighteenth century, returning to attack a number of gas instillations in the North Sea in an attempt to take over humanity.