A scientific research establishment has been established in the late twentieth century at Fetch Borough in the West Country of England. Run by the determined millionaire scientist Dr Fendleman, the other research associates are the chronology technician Thea Ransome, and palaeontologists Adam Colby and Maximilian Stael. Their primary research subject is a seemingly human skull that had been buried in volcanic sediment in Kenya some 12 million years earlier – making it 8 million years older than the perceived thinking on the history of man. Fendleman operates a time scanner to get a reading on the skull, causing a series of strange occurrences: Thea seems to be overcome by a strange affinity with the skull, which pulses with light, and collapses; while in a nearby forest a hitch-hiker is rendered immobile by an unseen monstrosity which consumes him.
The effect is felt in the TARDIS too, where the craft’s path is disturbed by the use of the scanner and the consequent hole in the time fabric. The Doctor is worried repeated use of the scanner will result in a time implosion and so pilots the TARDIS to the source of the disturbance. When it lands, he and his companion Leela venture outside to investigate. They soon encounter council worker Ted Moss, who tells them of the strange scientific establishment at Fetch Priory.
At the research establishment Thea is recovered but all the personnel are stunned to hear that Colby has found a corpse – seemingly drained of all life – during his morning constitutional with his dog. Fendleman appals Thea and Colby by first suggesting the body be moved as it is too close to Fetch Priory, and then organises private security cover for the Priory as well as persuading Stael to do a post mortem on the corpse. When this is done, Stael reports there is a small blister on the man’s neck and that, despite his recent death, the corpse is decomposing very rapidly. Fendleman decides Stael must hide the body and speak of the death to no-one. A little later the security squad has arrived at Fetch Priory, led by a guard called Mitchell. He gets into an argument with an old woman called Martha Tyler who is both a white witch and the cook at the Priory.
When night falls the Doctor and Leela decide to investigate the Priory itself. However, Thea has meanwhile activated the time scanner and it starts to power up, affecting both the skull and the time fields once more. Its image and hers seem to merge. Meanwhile, Leela has wandered off to a nearby cottage and when she enters a shotgun goes off. The Doctor is alone in the woods and is affected by the time distortion as he walks – but his legs soon stop working and he seems to be at the mercy of whatever creature killed the hiker.
The Doctor survives by forcing his legs to move but the creature instead attacks the Priory itself, killing Mitchell. Colby disconnects the time scanner before it causes more havoc, but he is aware of the strange trance that seems to have affected Thea. He returns her to consciousness and together they investigate the screams in the kitchen and find Mitchell’s body, decomposing rapidly. Thea starts to transform once more, at which point the Doctor arrives and takes command, telling Colby to be wary of her. Images are being transposed across her – the strange slug-like monstrosities that he names as Fendahleen. They disappear quite suddenly, but the Doctor is very worried, reflecting on the race history of his own people and the danger they pose. He warns Colby that within a year the creature could eliminate all but one life on the planet. His musings are interrupted when Fendleman and Stael arrive, ensuing the Doctor is imprisoned while they deal with a second body. Fendleman now explains to Colby his theory that the skull in the laboratory is not human – and therefore that mankind did not originate on Earth either. He is sure that the skull stored a vast amount of energy when it died some 12 million years earlier. Further, the skull has an imbedded pentagram in its structure. He also reveals he has been undertaking secret experiments on the skull with Stael.
Leela has meanwhile overpowered her assailant, local worker Ted Moss, who is waiting in the cottage for Martha Tyler. Her grandson, Jack Tyler, arrives and throws Moss out, then engages Leela in conversation until his grandmother returns. She arrives back in a deep fright, her mind shielded in fear, and Leela heads off to find the Doctor to see if he can help.
Back at the Priory, Thea has been overcome by a desire to activate the time scanner once more. When she returns to the room with the skull, Stael appears and chloroforms her. Meanwhile the Doctor has escaped his prison and starts to investigate the house. He soon finds the room with the skull too (though it is now empty) and when he touches the skull itself it sends massive spasms of pain through his body.
Leela finds the Doctor in agony and succeeds in breaking his physical link with the skull, ending his torment. He explains the skull is feeding on death itself and thus growing stronger. She takes him back to the Tyler cottage to tend to the shocked Martha Tyler. He succeeds in breaking her mental state by confronting her with normality. He then persuades Jack of his good intentions, warning that the area isn’t haunted but rather is subject to a time fissure which causes the manifestations of things that appear as ghosts. The Doctor and Leela then visit the TARDIS where he examines his records of the Fifth Planet of the solar system, which was where the Time Lords confronted and seemingly destroyed the skull and its source, a being called the Fendahl. The Time Lords created a time loop around the remnants of the planet to protect its secrets.
Stael has meanwhile taken the upper hand at the priory. He is the head of a local cult (one of whom is Ted Moss) and the cult has established a meeting place in the basement of the Priory. Stael has taken Thea there, tied up in the centre of a large pentagram. Colby and Fendleman are also taken to the basement and tied to stakes to witness the transformation of Stael into a god. His acolytes have trailed cables to the basement too, channelling the power of the time scanner, which Stael seems to believe will be the source of his new power. Fendleman now begins raving against Stael, warning him they are all pawns in the plan of the Fendahl to recreate itself, and in return his former deputy shoots him through the head. Stael now activates the time scanner again, once more causing Thea to transform into another being.
The Doctor and Leela return to the Priory and there find Martha and Jack. However, the danger is now multiplying as the scanner is running. Moments later a Fendahleen appears before them, advancing menacingly and oozing evil, and yet none of them can move their legs to flee.
The Doctor persuades them they can all still use their legs and they manage to escape the Fendahleen, killing it by shooting rock salt into its open maw. The Doctor explains that the Fendahl skull had created the creature during the process of restructuring Thea’s own skull as the Fendahl Core, and it is responsible for the deaths of the hiker and Mitchell. Meanwhile in the cellar Thea has become the god-like Fendahl Core, a powerful being that is able to teleport and transmit itself telepathically. Her eyes have transformed into large saucers of light and the Core uses its eyes to transform the coven members into small embryo Fendahleen. The Doctor and Leela reach the basement and manage to free Colby from the scene of carnage. Stael has looked into the Core’s eyes too and is starting to change into a Fendahleen; the Doctor gives him a gun to kill himself to prevent the full transformation. Stael’s death also means there aren’t enough Fendhaleen present to allow the full gestalt Fendhal to manifest itself.
The Doctor returns to the scanner room and switches the machine off then collects Leela, Colby, Jack and Martha. They all work together to keep the Fendahleen at bay with rock salt. The Doctor then explains the origin of the Fendahl. 12 million years earlier evolution turned in on itself and created a being capable of absorbing all energy. His people, the Time Lords, saw the danger of such a being and destroyed the Fifth Planet, hoping the Fendahl had perished too, but somehow the skull survived and projected itself to Earth. The evolution of mankind has been overshadowed ever since, with Fendleman (or “man of the Fendahl”), Stael and Thea Ransome being genetically predestined for their roles in the ensuing crisis.
The Doctor realises the only way the Fendahl can be defeated is by continuing to run the time scanner until it causes an implosion and destroys the Core and embryo Fendhaleen. He gets Colby to activate the scanner while he and Leela venture to the basement and seize the skull, using a lead-lined box to transport it from the domain of the Core. Fendhaleen and Core fail to prevent them making their escape and the Doctor, Leela, Colby, Jack and Martha meet back at Mrs Tyler’s house minutes later, where they witness the vast implosion and destruction of the Priory. The Doctor and Leela take their leave and the next journey of the TARDIS is to the heart of a supernova, where the Doctor deposits the skull, believing it will finally be destroyed.
Doctor Tom Baker (Fourth Doctor)
Companion Louise Jameson (Leela)
Denis Lill — Fendleman
Scott Fredericks — Max Stael
Wanda Ventham — Thea Ransome
Edward Arthur — Adam Colby
Daphne Heard — Martha Tyler
Geoff Hinsliff — Jack Tyler
Edward Evans — Ted Moss
Derek Martin— David Mitchell
Graham Simpson — Hiker
Writer Chris Boucher
Director George Spenton-Foster
Script editor Robert Holmes
Producer Graham Williams
Executive producer(s) None
Production code 4X
Series Season 15
Length 4 episodes, 25 minutes each
Originally broadcast October 29–November 19, 1977