The Cynrog are a particularly vicious race of aliens, being physically a dark grey-green colour with wrinkled skin, a pug nose, cat-like eyes and sharp teeth. Their conquest based on a warped religious crusade, the Cynrog have dominated entire galaxies in the name of the powerful and ruthless General Balor, who was worshipped as a god following his resurrection in a questionable accelerated genetic mutation experiment. Possessing powerful psychic-based technology, the Cynrog were capable of accessing the minds of others using their machines – although the evidence suggests that they were no more psychic than normal humans without technological assistance – and were also capable of channelling that mental energy to perform various actions.
The Cynrog first came to Earth when Balor’s ship crash-landed off the coast of a Welsh village in around the 1940s, leaving him badly injured and close to death. Using his technology, he was able to broadcast fragments of his mind into the minds of the children who had discovered his ship. As a result, although his body died, his mind was divided amongst the seven children who had witnessed the crash, each of them subsequently tormented by nightmares and other such difficulties over the course of their lives as Balor’s mind fought to come back together with its other ‘components’.
Eventually, the other Cynrog came to Earth at some point around the Second World War, making contact with Nathaniel Morton, one of the children who had been exposed to Balor’s ship when he crashed. Convincing him that they could not only remove the elements of Balor’s mind from him and his fellows, but also restore them to youth so that they could live the lives that their trauma had denied to them, the Cynrog – led by the aptly-named ‘nurse’ Peyne, a Priest Commander of the Third Cynrog Scientific Militia – set up a research facility in the nearby rectory. While Morton subtly drew his old friends back to him over the course of the next few decades, the Cynrog used a behaviour inhibitor set up in the nearby abandoned lighthouse to tap into the nightmares of the local children, generating monsters every night to discourage people from going out – as well as telepathically discouraging people from trying to seek help from outside – while simultaneously gathering energy from the childrens’ nightmares to create a new body for Balor (Morton and his old friends being too elderly to provide sufficient energy themselves).
This situation continued until the Tenth Doctor and Rose Tyler arrived in the village after the TARDIS’s telepathic circuits picked up the signals from the telepathic aerials of the behavioural inhibitor, causing Rose to dream of the lighthouse and prompting The Doctor to travel to the village to investigate the signals. Having escaped the nightmarish ‘monsters’ – mostly variations on themes such as giant insects – and reaching the local pub, The Doctor and Rose learned what was happening, as well as the belief that Morton was involved in the events in question. While Rose befriended Ali Hardy – the daughter of the owners of the pub – The Doctor, having failed to question Morton and only managing to get a brief look at his associates – now kept alive only by machinery – investigated the lighthouse with the aid of Brownyn – a woman in her seventies whose son, Jimmy, was taken from her by child protection because they thought she was a bad mother – discovering the Cynrog’s spaceship and the behavioural inhibitor that they had hidden on the island.
Back on land, while exploring an underground tunnel with Ali, Rose was captured by Miss Peyne, learning Peyne’s true identity and race before Peyne wired her up to the dream machine to learn the truth about her presence. Fortunately, Ali – who had been following Rose since she was captured – managed to rescue Rose, The Doctor simultaneously encouraging the adults to wake the children up to prevent the monsters being created while he travelled to Morton’s house, discovering Balor’s body and confronting Peyne about her plans. Outraged at The Doctor’s defiance, Peyne awoke Balor once again, but swiftly realising from his brutal behaviour that a fragment of his mind was still missing – the fragment having been hidden in the mind of the young Bronwyn, who had witnessed the crashed ship while hiding from the other children in the nearby bushes – Peyne attempted to use the energy of normal human minds as a substitute for the fragment. Unfortunately for Peyne, Balor’s mind was so weakened by the loss of that fragment of himself that Morton was able to gain control of the body instead, killing Peyne before turning on The Doctor. At the last minute, Ali, on Rose’s instructions, reprogrammed the dream inducer to tap into the minds of adults rather than children, sending all the adults to sleep and causing Balor’s new body to collapse before it was fully formed, the mundane problems of adults lacking the imagination of children that Balor required to properly manifest.
As a pleasant side-effect, due to Peyne reprogramming the machinery to search for Bronwyn while it was still carrying out its pre-programmed mission to rejuvenate Morton and his friends, the machinery drew the life force from Morton and the others and sent it to Bronwyn, restoring her to her youth during her pregnancy, providing her with a second chance at both life and motherhood. With Balor defeated – the last vestiges of his mind were transferred into The Doctor, who resolved to purge them from his subconscious when he returned to the TARDIS – The Doctor ordered the Cynrog to depart in their ship’s stasis chambers, confident that he would leave them with some very unpleasant nightmares for the journey home.