Written by Victor Pemberton
"This is a struggle for power, Miss Jones. Matter over mind!"
| Episode Title | Premiere Date |
| Episode 1 | 16/03/1968 |
| Episode 2 | 23/03/1968 |
| Episode 3 | 30/03/1968 |
| Episode 4 | 06/04/1968 |
| Episode 5 | 13/04/1968 |
| Episode 6 | 20/04/1968 |
The TARDIS brings the Doctor, Jamie and Victoria to the present-day North Sea coast. Something nasty is lurking in the gas pipelines of the North Sea, and before long the nearby refinery is under attack. The Doctor discovers that a form of living seaweed is at work, and that a number of the base personnel have been possessed. Can he and his friends work in time to prevent an entire take-over of Earth?
Cast & Crew
The Doctor: Patrick Troughton
Jamie McCrimmon: Frazer Hines
Victoria Waterfield: Deborah Watling
Robson: Victor Maddern
Harris: Roy Spencer
Maggie Harris: June Murphy
Van Lutyens: John Abineri
Quill: Bill Burridge
Oak: John Gill
Producer: Peter Bryant
Director: Hugh David
Scriptwriter: Victor Pemberton
