Jefferson (Danny Webb) opens fire on the approaching Ood who are possessed by the Beast. He kills them,
and he, Danny (Ronny Jhutti) and Rose (Billie Piper) then hear from Zack (Shaun Parkes) who informs them that the planet is
now stabilising around the black hole again. Jefferson recommends "Strategy 9" and Zack agrees, so the Base then makes contact
with the Doctor (David Tennant) and Ida (Claire Rushbrook) and discover that the Pit is open. Zack orders Ida to return under
the conditions of Strategy 9, but she is reluctant to obey, wanting to explore the Pit. The Doctor thinks on it for a while
before deciding they should follow Zack's order. Meanwhile, Jefferson turns on Toby (Will Thorp) with his rifle, but Rose
points out that he is no longer possessed. He's terrified by the ordeal, and tells them that he had the Devil inside his head.
The Beast, acting through the Ood, then takes control of the viewscreens to deliver a message to the crew.
The Doctor asks him which version of the Devil he is supposed to be, and he says he is all of them. He explains that he was
imprisoned before the creation of the universe before going on to taunt each of them about painful events from their past,
except Rose, who he predicts "will die in battle, so very soon." The message ends, and the Doctor tries to restore some confidence
and faith in the crew by explaining how the Beast just preys on basic fears and how they can rise above it, until the Beast
snaps the cable supporting the lift. The Doctor and Ida leap out of the lift as the cable comes crashing down, and Ida suggests
she ventures into the Pit as they only have one hour of oxygen left and not much left to lose. The Doctor disagrees and say
he will go instead.
Back on the base, Rose rallies the crew into action, getting Zack to restore the lights and Danny to find
a method of rendering the Ood unconscious. To administer the latter, they have to travel through the ventilation shaft below
to Ood Habitation, through discrete pockets of atmosphere created by Zack in order for them to breathe. The Ood follow them,
and Jefferson falls behind defending the rest of the crew. His final request is that the atmosphere be removed from his section
of the shaft to avoid "death by Ood", and Zack honours it. The rest of the crew barely escape the Ood, and Toby is almost
caught by them until his eyes go red again and he puts his finger on his lips to signal to them that he must not be harmed
as he is still possessed. Danny sets off the signal to paralyse the Ood just as they are about to enter Central Control in
pursuit of Zack, who was only armed with a single shot in a bolt gun.
Below, the Doctor reaches the end of the cable, but not the bottom of the Pit. Realising that he may only
be thirty feet from the bottom, a drop that he could survive, he detaches himself from the cable despite Ida's protests, and
drops the rest of the way, into the inpenetrable darkness. This happens just as Zack and Rose make contact, so Ida tells them
what happened, only to be told that she will run out of air soon and that there is no way of reaching or rescuing her. Zack
then determines that the survivors should leave the planet and ensure no one ever goes back, but Rose refuses to go, not believing
that the Doctor is dead. Danny administers a sedative on her and Zack carries her to the rocket they will depart in. At the
bottom of the Pit, the Doctor wakes up and finds he is alive and able to breathe the atmosphere. He explores the cave and
finds a huge demon chained to the cavern wall; the Beast.
On the rocket, Rose regains consciousness as it launches, and is restrained despite her threats to shoot
Zack with the bolt gun she found discarded near to her. The Doctor begins to speak to the Beast, but is puzzled by his lack
of a response. He realises it is only the body that is imprisoned, and the Beast's mind is what has been possessing Toby and
the Ood. He comes to the conclusion that he can breathe here not because the Beast needs him for something, but because he
is trying to escape, and his jailers want the Doctor to stop him. He's about to do so by smashing the vases that are the gateway
to the prison, when he realises that doing so would mean the loss of the rocket's protection from the black hole. Onboard
the rocket itself, the Beast's mind is delighted with the prospect of making it to Earth to further corrupt and terrify humans,
but when the rocket is just about to move out of range of the black hole, the Doctor smashes the vases, violating the orbit
of the planet around the black hole.
The rocket starts to be dragged backwards into the black hole, and the Beast's mind is enraged, making Toby
take on the appearance he had when he was first possessed. Rose takes the bolt gun and shoots the windscreen of the rocket
before undoing Toby's seatbelt. Toby is sucked out into space, and the rocket continues to move towards the black hole. In
the Pit, Ida finally collapses, just as further below, the Doctor is thrown backwards against something. He turns around and
discovers it's the TARDIS. Just as the rocket is about to enter the black hole, it stops, and the Doctor announces he is towing
it using the TARDIS via a comms link. Rose is delighted to hear the Doctor again, and Danny and Zack are delighted to hear
that Ida will be OK, as the Doctor has rescued her. Rose re-enters the TARDIS and hugs the Doctor. The two crews say their
goodbyes, and Rose again asks why the Beast said she would die in battle. The Doctor reassures her that it was lying, and
they take off in the TARDIS, leaving the impossible planet behind...