Clara wakes to find herself hanging upside down, with Missy sitting across from her.
The Mistress informs her that she adjusted their vortex manipulators to use the Dalek's energy wave to teleport them to safety. However, it's up to Missy and Clara to free the Doctor from the heart of the evil Dalek city.
Meanwhile, Davros torments the Doctor reminding him how he abandoned that young boy all those years ago. "And here you are at the end, but this time I have you at my mercy" the villain continued. The Doctor forces Davros from his chair.
Alarms ring out throughout the city, as the Daleks panic over their creators safety.
The Doctor spins into the room, mocking his enemies as they attempt to kill him. Luckily, the chair's force field deflects the death rays. However, Colony Sarff's agents are everywhere and they slither around the Doctor bringing his fun to an end.
Elsewhere, Missy and Clara attempt to reach the Doctor via the city's sewers which consists of decomposing Daleks. "Interestingly, the Dalek word for sewer is the same as their word for graveyard" Missy informs Clara. The Mistress then uses Clara as bait to kill a Dalek. She removes the tiny creature and has the Doctor's companion enter its tank-like shell. Most of Clara's words now translate to "Exterminate!"
Davros reminds the Doctor he's dying and would like to conclude their business together. He mentions he's connected to the life force of every Dalek on the planet and talks genocide. "Genocide as a choice" Davros whispers. "Are you ready to be a God?"
Naturally, the Doctor hesitates and Davros blames his shame. "I didn’t come here because I’m ashamed – a bit of shame never hurt anyone. I came because you’re sick, and you asked" the Doctor informs his nemesis. Compassion will kill the Doctor in the end Davros replies.
During their last conversation, the Doctor mentions that Gallifrey is back and it's safe. Davros congratulates him, which confuses the Doctor. He asks his longtime enemy to approach so he can look on him with his own eyes. "Protect your own, as I have sought to protect mine" Davros says. "Did I do right Doctor? Tell me, was I right? I need to know before the end. Am I a good man?" he continues.
Ultimately, the dying man confides he had hoped to witness one last sunrise. Determined to make that happen for the little boy he once met, the Doctor uses a bit of regeneration energy to revive him. Davros cackles menacingly since the Doctor's compassion just got the better of him. Every Dalek on Skaro soon begins to glow with the lifeforce of the Time Lords.
Missy arrives in time to free the Doctor, who tells Davros he knew exactly what the trickster was up to. By waking up generations of Daleks in the sewers, the Doctor caused the Dalek City to collapse in on itself.
A lone Dalek approaches the Doctor and Missy. As Clara screams "I am Clara" from inside, all he hears is "I am a Dalek." Missy attempts to lie, telling the Doctor Clara was killed, but suddenly the Dalek says "mercy." The Doctor realizes Clara is inside and warns Missy to run.
"In a way, this is why I gave her to you in the first place; to make you see. A friend inside the enemy, the enemy inside the friend. Everyone’s a bit of both. Everyone's a hybrid" Missy says. As the city crumbles, the Mistress comes up with one last clever idea.
The Doctor and Clara run toward the TARDIS, which quickly reassembles itself.
Returning to that old battlefield, the Doctor wipes out the hand grenades and saves young Davros. "Are you the enemy?" the boy asks. "I'm not sure that any of that matters. Friends. Enemies. So long as there's mercy" the Doctor tells him.