Doctor: David Tennant (Tenth Doctor)
Companion: Freema Agyeman (Martha Jones)
Others
Michelle Collins – Kath McDonnell
Adjoa Andoh – Francine Jones
William Ash – Riley Vashtee
Anthony Flanagan – Orin Scannell
Matthew Chambers – Korwin McDonnell[1]
Vinette Robinson – Abi Lerner
Gary Powell – Dev Ashton
Rebecca Oldfield – Erina Lessak
Elize du Toit – Sinister Woman
Joshua Hill – Voice of countdown
Production
Directed by Graeme Harper
Written by Chris Chibnall
Script editor Simon Winstone
Produced by Phil Collinson
Executive producer(s) Russell T Davies
Julie Gardner
Incidental music composer Murray Gold
Production code 3.7
Series Series 3
Length 45 minutes
Originally broadcast 19 May 2007
The Doctor and Martha receive a distress signal from the S.S. Pentallian, a human spacecraft that is hurtling towards the star of the Torajii system. The Doctor pilots the TARDIS towards it to help, but after arriving they are separated from the TARDIS by the rising temperatures on the ship. The ship's engines have failed and they have only 42 minutes left before the ship plunges into the star. They need to reach the bridge controls but find themselves separated from them by thirty deadlocked doors that are each password encoded. Martha teams with Riley to work their way through the doors, having to answer pop quiz questions in order to open each door. The Doctor helps the engineering team try to repair the engines. Martha uses her modified mobile phone to call her mother Francine on present-day Earth to answer one of the questions. Francine asks questions about the Doctor that Martha ignores.
One of the crew, Captain McDonnell's husband, Korwin, has been infected with something that is causing his body temperature to rise to incredible levels. They attempt to sedate him while they continue the repairs, but the sedative doesn't work and Korwin escapes. He dons a welding helmet and starts killing crew members before infecting a man named Ashton. As Martha and Riley continue to work through the doors, they encounter Ashton and take shelter in a nearby escape pod. Ashton is able to launch the pod despite Riley's attempts to stop him. As the pod falls towards the star, Martha calls her mother and apologises but hangs up when Francine again asks Martha for more information on the Doctor. The Doctor learns of Martha's situation and puts on a spacesuit before going outside the ship and activating a magnetic control that recovers the pod. As the Doctor returns to the spacecraft, he looks at the sun and finds himself infected. He learns that the star is actually a living being and that the crew drew the star's heart to use as fuel despite it being illegal to do so, and now the star is trying to recover its lost parts. Martha puts the Doctor into a stasis chamber to prevent him from regenerating, but Korwin appears and disables the chamber. The Doctor insists that Martha leave him and warns the crew to dump the fuel, which should allow them to escape.
Martha relays the Doctor's message to the crew. McDonnell encounters Korwin and apologises to everyone before blowing Korwin and herself out of the airlock. The ship vents its fuel and the engines restart, allowing them to pull away from the star. The presence inside the Doctor slowly dissipates as the ship moves away. The Doctor, Martha, and the remaining crew say their goodbyes as the crew requests a refuel to continue on. The Doctor and Martha depart in the TARDIS, and the Doctor gives Martha one of the TARDIS keys. Martha places another call to her mother, and learns that it is Election Day. After Martha's call, a woman who was monitoring Francine's phone confiscates it and leaves.
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