Doctor: David Tennant (Tenth Doctor)
Companion: Billie Piper (Rose Tyler)
Camille Coduri – Jackie Tyler
Noel Clarke – Mickey Smith
Tracy-Ann Oberman – Yvonne Hartman
Raji James – Dr Rajesh Singh
Freema Agyeman – Adeola Oshodi
Hadley Fraser – Gareth
Oliver Mellor – Matt
Barbara Windsor – Peggy Mitchell
Derek Acorah, Alistair Appleton, Trisha Goddard – themselves
Directed by Graeme Harper
Written by Russell T Davies
Script editor Helen Raynor
Produced by Phil Collinson
Executive producer(s) Russell T Davies
Incidental music composer Murray Gold
Series Series 2
Length 1st of 2-part story, 45 minutes
Originally broadcast 1 July 2006
The episode begins with a cold open in which Rose, via narration, recollects her life with the Doctor and her belief that they would always be travelling together. She then mentions that this episode is "the story of how I died".
Rose Tyler and the Doctor decide to visit Rose's mother Jackie. Jackie is pleased to see them, but makes a strangely happy remark that her deceased father will be joining them shortly. Despite Rose's protestations that her grandfather is dead, Jackie insists that he has returned and has been visiting her for some time. A vaguely humanoid and luminous silhouette appears in the flat, surprising both the Doctor and Rose but delighting Jackie before disappearing. TV broadcasts confirm that this is a worldwide phenomenon and Jackie explains that a few months previously millions of ghosts began appearing all over the world. Humans have come to accept them and believe that they are the manifestations of loved ones.
The Doctor dismisses the possibility that these are ghosts and conducts an experiment with the help of the TARDIS. He attempts to trap a ghost and determines that they are not ghosts but are impressions of something forcing its way into this universe. The Doctor tracks the signal back and uses the TARDIS to travel there, arriving at the Torchwood Institute. The Doctor introduces himself and tells everyone that Jackie is Rose, his companion. They are taken by soldiers to see Torchwood's current director Yvonne Hartman, while the TARDIS is impounded with Rose inside. Ms. Hartman shows the Doctor the source of the ghost energy, an invisible breach in the universe through which a mysterious spherical object has arrived. The Doctor inspects the sphere, declaring it to be a "Void ship"—which, according to him, is impossible. It is designed to exist in the space between universes, a nothingness called the Void. The ship is completely undetectable by all scientific instruments. Torchwood has no explanation for what the sphere is or how it got there, but they claim responsibility for the ghosts. Torchwood has been conducting experiments on the breach, forcing it open in an attempt to harness it as a source of energy. Ms. Hartman also reveals to the Doctor that his encounter with Queen Victoria in "Tooth and Claw" made him an enemy of the state and was the catalyst for the creation of Torchwood. Unbeknownst to all at this point, an unseen party has infiltrated the institute and has been successful in subverting three Torchwood staff.
Meanwhile, Rose slips out of the TARDIS and uses a lab coat she found to masquerade as an employee to explore Torchwood. She gains access to the sphere chamber with the Doctor's psychic paper, but is detained by a Dr. Singh. He discovers that Rose is an imposter and informs Ms. Hartman of her presence. Dr. Singh then asks his colleague Samuel, whom Rose recognises as Mickey Smith, to seal the doors. Ms. Hartman questions the Doctor, who admits that the woman in the sphere chamber is really Rose and that the woman with him in her office is Rose's mum Jackie. In the command centre, the three employees under manipulation initiate an unscheduled ghost shift and forcibly open the breach. The extended shift causes millions of ghosts to appear across the globe before they materialise into their true form, the Cybermen. At the same time the Cybermen arrive the Void ship suddenly activates and begins to open. The Cybermen take control of Torchwood and order the complete surrender of humanity for conversion. The Doctor, puzzled at how the Cybermen could have created an advanced piece of technology like the Void ship, asks the Cyber Leader how they were able to build it. The Cyber Leader responds that the sphere does not belong to them. The Cybermen are similarly oblivious to the origins of the sphere and that they merely followed its course through the breach.
In the sphere chamber, Mickey explains to Rose that after a battle in the parallel universe the Cybermen mysteriously disappeared. He happened upon their means of escape and returned to his native universe with the intention of stopping them. Mickey believes that the Cybermen are in control of the sphere and produces a gun to destroy whatever is in it. Rose is horrified when the sphere opens and reveals its occupants to be a quartet of Daleks, who identify their location as Earth and begin chanting,