Reset (Torchwood)

A series of mysterious deaths in Cardiff prompts Jack to recruit UNIT medical specialist Martha Jones. The victims appear to have died from toxic shock, but their medical records have been deleted and closer examination by Owen and Martha reveals that all have been murdered. Further investigation shows that the victims have previously suffered from incurable diseases such as diabetes and HIV, but were cured of them prior to their deaths. All were participants in clinical drug trials at a secure medical research facility called The Pharm, run by the well respected medical researcher, Professor Copley. One victim, still alive when Torchwood find her, dies while being questioned and fly-like creatures erupt from her mouth.

Jack and Owen confront the professor who claims only to use human subjects for advanced clinical trials of disease curing drugs, but Jack detects a strong presence of alien life forms within The Pharm, and the facility's security system proves to be beyond the ability of Torchwood to hack from the outside. Martha offers to infiltrate the facility disguised as a human test subject and is accepted after claiming to be infected with hepatitis. Once inside, Martha discovers that The Pharm uses a substance called "Reset" that releases alien parasites called Mayflies into the host's body. The parasites cure the patient of any diseases and restores them to "factory settings", but at the price of infecting the patient with the parasite. When the eggs hatch, the creatures destroy the host. Copley determines that Martha's body has experienced the effects of time travel and further connects Martha to Jack and Torchwood. Feeling that she would be a remarkable test subject, Copley injects her with multiple doses of Reset, curious to determine the effect of Mayflies on her immune system.

With The Pharm's computer systems compromised by Martha, Torchwood discover the assassin employed by The Pharm to dispose of research subjects and realise he is about to kill the last living test subject. Ianto and Gwen apprehend the killer and return him to the Hub for questioning. He agrees (under duress) to help Torchwood to infiltrate The Pharm and rescue Martha, but it becomes clear that he is infected with Mayflies, likely contracted from one of his previous victims, and is about to die. Owen attempts to remove the creature with the singularity scalpel, but fails to operate the device correctly, leaving the Mayfly alive and killing the man. The team rushes to the Pharm hidden in the assassin's vehicle, using the dead man in the driver's seat to fool the security guards into letting them inside the compound.

Within the Pharm, they find numerous tormented aliens being used to produce various test substances, including the mature Mayfly that is the source of Reset. They also find Martha near death in the professor's laboratory and Owen this time is able to successfully use the singularity scalpel to neutralise the Mayfly within her. Jack orders Tosh to shut down the Pharm, euthanizing all of the trapped aliens and crashing all computer systems. Before the team can depart, though, they are stopped at gunpoint by Professor Copley. Owen places himself between Martha and the gun while attempting to reason with the professor. Copley fires, hitting Owen in the chest and Jack responds by firing and killing Copley. Martha and the Torchwood team try to save Owen, but their efforts are unsuccessful.

• Jack refers to meeting Christopher Isherwood, and attributes the quotations "I am a camera" (in its full form, "I am a camera with its shutter open, quite passive, recording, not thinking.", from "Berlin Diary", 1930) and "It's not the getting in, it's the getting out" to him. Isherwood would later be portrayed by actor Matt Smith (better known as the Eleventh Doctor), in the 2011 BBC TV film Christopher and His Kind.