The Clerkenwell House Of Detention, a dark, damp and disused prison site, was originally built in 1845 and soon to became London's biggest remand prison with up to 10,000 prisoners a year. Records of incarceration on the site however go back as far as the 17th where many thousands were subject to terror and torment. Most of it was demolished in 1890 but the wardens residence and the entire underground level of the prison was left intact. Some underground cells became air raid shelters during the Second World War, and more recently In 1983 the doors were opened to tourists.

The investigation begins at the entrance to the prison, where Derek picks up on a early 18th Century highwayman called Jack Shepherd. Upon entering the cell blocks Derek begins to sense significant negative energies, and in particular the presence of a highly malevolent spirit. This entity was apparently responsible for great suffering and torment within the prison, a prisoner turned jailor who would mutilate and abuse inmates for his own pleasure. As the team move deeper into the jail Derek makes reference to an explosion that occurred on the site and connected with the energies of people suffering and choking in he fumes. The dark entity then begins to make its presence felt more strongly, a despicable man by the name of Michael from the 1860’s who warns Derek that the crew would succumb to his fury and rage, specifically the female members. The footage at this point is cut while Derek explains in graphic detail the images and words he is being given by this reprobate. As the investigation progresses Derek is made aware of a second negative energy called Joseph, who has apparently been called upon by Michael. At this point Karl appears to be struck by unseen hands, and on investigation has suffered a blow to the forehead which he likens to being cut by a razor blade. The negative atmosphere becomes even more oppressive when an apparent third negative soul enters the fray. Confusion and fear reign as the team roam the dark cells, compelled by the strange malfunction of their two-way radios.