EPISODE: The Sea Devils: Episode Four
OVERALL EPISODE NUMBER: 315
STORY NUMBER: 062
TRANSMITTED: 18 March 1972
WRITER: Malcolm Hulke
DIRECTOR: Michael Briant
SCRIPT EDITOR: Terrance Dicks
PRODUCER: Barry Letts
FORMAT: DVD: Doctor Who - Beneath the Surface (The Silurians / The Sea Devils / Warriors of the Deep)
Episode Format: 625 video
The Doctor uses his Sonic Screwdriver to detect where the mines are enabling him & Jo to cross the minefield and escape. When the Sea Devil pursues them The Doctor detonates some mines to scare it off. As Captain Hart grows concerned about his missing submarine it's command deck is breached by the Sea Devils. The Sea Devils direct the submarine to take them to a specific location. Returning to the Naval base Hart still won't believe the Doctor's story but the base detects the moving Submarine's radar trace as it surfaces near the castle/prison. More Sea Devils come up out of the sea onto the beach is response to the Master's summoning device. They storm the prison killing Trenchard & his guards then freeing the Master. Hart investigates the prison discovering what had happened as the submarine is detected moving towards the sea fort. The Doctor is taken on a diving vessel to the sea fort. The Doctor descends in a diving bell to the ocean floor. Reaching the bottom the Doctor sights a Sea Devil, but his contact with the surface is lost. Captain Hart has the diving bell brought back up but when it's opened it's found to be empty.....
Most six part Doctor Who stories feel in some way like they're in two halves with a change of location or emphasis occurring at some point. This episode feels a lot like it's a bridge between the two halves of the Sea Devils: the prison & Trenchard are removed here, Hart starts to believe and we're introduced to the diving vessel.
The locations for this story can all be found in a small area centring around Portsmouth & the Isle of white. The prison exteriors are Norris Castle on the Isle of White with Portsmouth's Naval Gunnery Range serving as the Naval base. The beach used for the Sea Devils coming ashore and the minefield was White Cliff Bay on the Isle of white. While filming the sequence where he throws his cloak over barbed wire Jon Pertwee injured his ribs on what the accident report describes as "a six inch metal tube" in his pocket - the sonic screwdriver. One location in this story is no longer in existence: The diving vessel HMS Reclaim was broken up for scrap in 1982.