The Doctor (Christopher Eccleston) faces the Daleks as he fights for Rose’s life. He and Jack (John Barrowman) materialize the TARDIS on board the Dalek command ship outside the Solar System, where they find Rose (Billie Piper)... and the Daleks’ master, the Emperor Dalek, who reveals that he also escaped destruction at the end of the Time War, and has slowly been using humanity to rebuild the Dalek species. Except now, the Dalek Emperor believes he’s a god.

The TARDIS escapes back to the Game Station, where the Doctor realises he can create a weapon capable of destroying the Daleks, and Jack attempts to lead a defence against the imminent Dalek onslaught. As Jack attempts to incite volunteers to help, Rose is sent back in time by the Doctor to the present day, fulfilling a request Jackie Tyler (Camille Coduri) made upon him to protect her daughter. Rose is consoled by Jackie and Mickey (Noel Clarke), but she’s determined to return to him.

The Dalek Emperor realises what the Doctor is planning: a pulse of energy that will not only decimate the Daleks but also kill off all life on Earth. The Doctor is given the choice to make while Jack and the small group of rebels still on the station attempt to stop them from their assault. Unfortunately, the Daleks make their way in, killing everyone in the process, including Jack.

In a local playground in London, Rose and Mickey discover the words ‘bad wolf’ written on the playground and Rose realises what it is: a message. She attempts to restart the TARDIS by opening its console, to no avail. Later, Jackie realises what the Doctor means to her as she helps Rose attempt to open the console, sending the time ship back toward the future.

The TARDIS arrives as Rose peers into the heart of the TARDIS and absorbs the Time Vortex. This strangely altered Rose confesses that she herself is responsible for ‘bad wolf,’ scattering the message across time so that she herself would see it and return for the Doctor. With almost godlike energy, Rose reaches across time and space and utterly destroys the Daleks, the Emperor and their fleet – as well as breathes new life into Jack’s lifeless body – but before the vortex finally consumes her, the Doctor kisses her, which releases the energy into himself. He then sends the energy back into the Vortex, but not before damage is done. The TARDIS leaves the station, leaving behind Jack Harkness who neither realises is still alive.

As the TARDIS travels through the Time Vortex, the Doctor begins a breakdown. While the helpless Rose watches, he bids farewell to her, and then begins to regenerate into a new body...