Picking up from where we left off, Sutekh blows deadly dust that turns anyone it touches into ashes.

The Doctor and Mel escape, but UNIT is not so lucky. They try to fight Sutekh with their guns but run out of ammo and eveyrone appears to be killed, even Kate who says goodbye to the Doctor before she dies.

At the Sunday house, Cherry asks Mrs. FLood who se really is but Mrs. Flood is turned to dust before she can answer. Cherry too. Carla is killed outside.

The Doctor arrives at UNIT HQ. Ruby is the only one safe because she was in the Time Window. The Doctor goes into the TARDIS in the Time Window and realizes something. He comes out and tells Ruby the TARDIS is made of her memories -- remember harder.

Ruby is able to remember the TARDIS on the night of her birth, but then Sutekh shows up on top of it. Sutekh says that when the Doctor supposedly banished him in the Time Tunnel during Pyramids of Mars, he attached himself to the TARDIS and learned all its secrets while evolving into a god, proving one fan theory right. He looked into the Time Vortex and learned its secrets. He learned who Susan was to the Doctor and created a copy of Susan Triad every place the Doctor landed -- his army of angels of death.

The Doctor taunts Sutekh about not killing him. When Sutekh lashes out, he, Ruby, and Mel run into a makeshift TARDIS made from memory. The Doctor doesn't know if it'll fly but demateralizes anyway. He explains what Sutekh did but realizes the dust of death is spreading over the Earth and there is nothing he can do -- everyone is dead.

The Doctor balmes himself. Every planet he ever traveled to is dead. The universe is completely dead. Mel and Ruby try to tell him it's not his fault but he won't listen.

The TARDIS lands somewhere and he puts on a monk's habit and goes out. There's a woman still alive. She says her memory is fialing. She doesn't know who or where she is and can't remember the name of her husband or her child. She says the death wave takes facts away too. She gives the Doctor a spoon, then realizes she forgot that her daughter is dead and says she's ready to die. She says he has a nice face. He swears as she turns to dust that he will save the universe with this spoon. (!)

The Doctor uses the spoon to plug into the TARDIS scanner so he can stabilize the TARDIS. It shows Ruby's memories but won't show them to him. Ruby keeps seeing the hooded figure who is supposedly her mother pointing. The Doctor says Sutekh is frustrated that he can't see her face so he can't kill her. The memory device suddenly shows the evil prime minister from 73 Yards, whom Ruby doesn't remember meeting. The Doctor realizes the guy ordered compulsory DNA testing so Ruby's mother should be in the registry even if the planet is dead. He takes the TARDIS to 2046 to see what he can find out, while Sutekh appears to be trying to use Melanie to get to the Doctor and find out the name of the woman he can't kill.

The Doctor does a finger stick and puts Ruby's blood into the DNA database, while outside Sutekh keeps calling to Melanie. It begins to snow and Ruby's cloister bell carol starts playing. Melanie starts freezing while Sutekh demands Melanie submit. Just as Ruby finds her mother's name, a Sutekh-possessed Melanie shows up and the Doctor says he loved Melanie and is so sorry she is dead.

Sutekh demands to know the name of Ruby's mother so that he can kill her, Ruby, and the Doctor. The Doctor pleads with him but he immobilizes him with a torturous green light. Ruby says she will give him the name. The Doctor says no! Ruby pretends she will do it but at the last second breaks the screen with the information and calls Sutekh the god of nothing.

Sutekh is angry and he and his minions go after the Doctor, who uses his whistle and the intelligent rope to tie Sutekh to the end of the TARDIS while he and Ruby retake their machine. The Doctor says the death of death is life so as he travels through time and space, life is restored! Melanie and Susan Triad and Rose and Kate and the rest of UNIT are resurrected. All the planets are restored and the Doctor sees the kind woman from before playing with her infant daughter in the grass. However, he must become a monster now. He must kill Sutekh. He opens the door and tells Sutekh that Sutekh has won as the Doctor wants to be better than him but cannot be. He cuts the rope and Sutekh tumbles into the nothingness of space.

At UNIT, the Doctor and Melanie have returned, along with Susan Triad, who asks is she still herself? The Doctor says she is. Kate invites her to work at UNIT. She says she will make the tea. Colonel Ibriham does not like the tea she has made.

Morris finishes Ruby's DNA analysis and learns that her mother was a 15-year-old girl named Louise Miller. Ruby doesn't understand. She is so ordinary, a teenage girl who got pregnant and was scared of her stepfather so thought it was best to give up the baby. The Doctor says that them believing how important she was made her able to defeat Sutekh. Ruby says she was pointing at you though. No, she was pointing at the sign. She was naming her baby Ruby after Ruby Road. Ruby cries.

The Doctor takes Ruby in the TARDIS to find her mother. He doesn't think talking to her is a good idea but Ruby doesn't listen. She goes into a coffee shop where Louise is and orders a cappcuino with the name Ruby and tells Louise she was named after Ruby Road. Louise cries and says she's so sorry. RUby tells her not to be.

Everyone celebrates at Ruby's house, but the Doctor is in the TARDIS. Ruby wants to go on more adventures with him but learns that they have found her father, who never knew she existed. The Doctor tells her her place is here at home. Ruby cries. Will she ever see him again? He promises he will come back to visit. Ruby has taught him to think of family in a different way and he now knows that abandoning his granddaughter was a mistake. Ruby says she loves him. She leaves and cries that he is gone.

Mrs. Flood narrates, saying that Ruby's story has a happy ending but she's sorry to say the Doctor's ends in absolute terror...

The credits inform us DOCTOR WHO WILL RETURN.