PREVIOUSLY ON DOCTOR WHO:
While the Doctor continues to regenerate backwards, he and Clara devise a plan to alter the Doctor's chameleon arch to stop the reverse-regeneration process. Currently in the body of his War Doctor incarnation, the time travellers arrive on a future spaceship in search of the first necessary part, only to encounter a massive explosion when the ship comes under attack.
Clara sat up and saw the flaming wreckage of the bridge through the hole blown through the wall. Dead bodies were strung everywhere, and the only thing keeping everything from being sucked into the vacuum of space was one of the saucer ships docking up to the open hole in the bridge.
The Doctor pulled his head up, and Clara now saw that he had changed his face again. He was now much younger and had wavy, shoulder-length brown hair. Clara rationalized that she had missed this latest regeneration in the explosion.
The Doctor ran his fingers through his long hair and smiled. "Right, just as well. That last body wasn't very much suited for running."
"SEEK AND LOCATE SURVIVORS," a robotic voice shouted from within the destroyed bridge. "ALL HUMANS MUST BE EX-TER-MIN-ATED!"
The Doctor and Clara both recognized that shrill, grating drone. "Oh no," the Doctor said as he got to his feet.
"WAIT!" another similar voice said. "MY SENSORS ARE INDICATING A TIME LORD IN THE AREA."
As the Doctor helped Clara get up, a group of Daleks hovered out from the bridge, the fires flickering off of their copper domes. Their heads swiveled around and locked onto the Doctor and Clara with their glowing blue eyestalks.
"IT IS THE DOCTOR!" one of the Daleks exclaimed. "EX-TER-MIN-ATE THE PREDATOR OF THE DALEKS! EX-TER-MIN-ATE!"
"Well," the Doctor said, grabbing Clara's hand, "time to break in this new body."
He sprinted down the hallway, taking Clara with him. The duo left the slow-moving Daleks behind him, but the dome-shaped killers still pursued them with laser shots and cries of "EX-TER-MIN-ATE!"
The were nearing the end of the hallway when the wall in front of them slid open and a platoon of heavily-armed soldiers exited in a shimmering beam of light.
One of the soldiers at the head of the group pointed his gun defensively. "Who are you? What are you doing here?"
"Escaping the Daleks," the Doctor said quickly. "They're coming this way."
As if on cue, the Daleks' screeching voices got louder as they approached.
"Battle positions, men!" the lead soldier said as the group bounded further down the hall. "Leave no survivors!"
As the soldiers charged and open-fired on the incoming invaders, the Doctor and Clara slipped into the chamber in the wall. The top and bottom were decorated in shimmering roundels, and a multi-buttoned control panel was beside the door.
"Teleportation elevator," the Doctor said as he ran his hand along the many buttons. "Very Star Trek. Now let's see…Where's maintenance at?"
"Doctor?" Clara asked with urgency. "The Daleks? Hurry?"
As the sounds of lasers and Dalek cries got closer, the Doctor found the button he was looking for. "Ah, here it is!"
He pressed the button and everything around the two travellers turned white and shimmering. Clara felt her insides jump into her throat for a second before the ride was over.
The light faded and they exited the elevator into a large room filled with grey-garbed officers. In the center of the room was a massive generator, and people worked at various stations, tweaking and modifying futuristic machinery.
The Doctor ran into the room and shouted, "The Daleks have breached the ship! Everyone head for the escape pods! It's your only chance for survival!"
The room erupted in a panic as engineers bolted for the elevator. Flashes of light carried them away in large numbers until the room was empty save for the Doctor and Clara. The only sound came from the whirring and clinking of the machines.
"We've only got a short while," the Doctor said as he started searching about the room. "Fortunately for us, Daleks can't really work elevators, but there's more than one way of getting down here."
As the Doctor tipped over boxes and scanned machines with his sonic screwdriver, Clara asked, "What exactly are we looking for?"
"An overclocker," the Doctor stated. "It overclocks things; modifies things past their potential."
"I got that," Clara said, meandering over to a table. "But what does it look like?"
"Well, it'll look somewhat like a bended pipe," the Doctor said as he rummaged around a desk. "Only it'll most likely have an electronic counter and ends that you can plug into machines."
"Like this?" Clara held up a machine that looked exactly like the Doctor had described.
He whipped around and darted for her. "Clara Oswald, I could kiss you," he said, snatching the device out of her hand.
"Maybe later," Clara remarked. "We should get out of here first—"
"THE DOCTOR HAS BE LOCATED!" a Dalek voice sounded.
The travellers turned to see a group of Daleks entering the room through a manual entrance, blasting lasers from their arms.
"Well, our job is done here," the Doctor said. He gripped Clara's hand and dashed into the elevator.
The Time Lord clicked the button for the top floor just as a Dalek shrieked, "THE DOCTOR IS ESCAPING! EX-TER-MIN-ATE THE ELEVATOR!"
The Doctor and Clara teleported away and wound up back on the top floor. They leapt out and dashed down the hallway. They rounded a corner and the TARDIS appeared in their vision.
As they neared the time machine, the Doctor's skin started to glow. He didn't stop running, but as he continued, he looked to be in pain.
"Come on," the Doctor grunted to himself. "Almost there."
Clara threw open the TARDIS door and she entered. The Doctor's regeneration exploded and he flopped into the time machine.
Clara moved to help the Doctor up, but he managed to upright himself before she could get any closer. His new form had a wider, mousy face and dark, receding hair. He appeared shorter than he hid before.
"You okay?" Clara asked.
"Yeah," the Doctor said, closing the door. "Word of caution: Don't regenerate and run at the same time."
While the Daleks' cries echoed outside the TARDIS, the Doctor frantically pressed buttons and pulled levers on the console.
"Clara," he ordered. "This is very important. In that closet over there, there is a box on the bottom of the shelf. I need you to bring it to me."
Clara vanished down the corridor as the Doctor worked on the console. The TARDIS began to dematerialize as the machine wheezed and groaned.
Clara reappeared a moment later carrying a small velvet box. "This one, Doctor?" she asked.
"Yes," the Doctor said, taking the box. "Thank you, my dear."
He opened the box and produced a light-colored panama hat. He placed it on his head and curled the brim upward. He grinned as he viewed his reflection in the monitor.
"Really?" Clara asked.
"I needed a hat," the Doctor said defensively. "I'm balding now, Clara."
Clara rolled her eyes. "So what's next?"
"Now we need a molecular stabilizer," the Doctor explained. "They're commonly found in technologies used by Cronitites, a close cousin of the Carrionites. I know where we can find one."
"So where are we off to?"
The TARDIS stopped wheezing. "16th century Germany," the Doctor said.
"Please, Witch Heziah," Jakob pleaded on his knees. "Have mercy, for I am unable to pay you this month."
Heziah rubbed her gnarled chin and moved her fingers up her bumpy staff. "You disappoint me, Jakob. For that, I must punish you."
Jakob back up in her small hut, his feet crunching against the straw floor. "No please, mighty witch! Have mercy!"
Heziah lowered the end of her staff at the boy. "You are hereby punished by the Great Witch Heziah! For your insolence, you shall spend the rest of your days as a measly toad!"
The end of her staff erupted in light and enveloped Jakob. He yelped out in pain as his form twisted and shifted, shrinking down until he had become a warty toad. He hopped to the side of the room, croaking sadly.
Heziah cackled to herself, but her laughter was cut off when her hut filled with an awful groaning sound. Wind kicked up from seemingly nowhere as a blue box slowly flickered into existence before her. Her dark soul filled with dread.
When the box had fully materialized, two beings exited it: a short, mousy man dressed in a dark coat and vest, and a young girl with dark hair dressed in a skirt.
Heziah hissed at them and waved her staff. "Be gone, Time Lord! Your Time War destroyed my planet, and I will not have you bring that breed of destruction to my new home!"
"If you know what I am, then you know the kind of power I bring," the Doctor said. "So I would think it wise of you to give me exactly what I want before the full wrath of a Time Lord is wrought upon your house." He held out his open hand. "Your staff, please."
Reluctantly and with a sneer on her face, Heziah handed the Doctor her staff. The Doctor ran his screwdriver along the length of the staff until he opened a panel on one of the staff's bumps. He buzzed his screwdriver inside the crevice and pulled out a small, dowel-like device.
"Here we are," the Doctor held up the object and handed the staff back to the Cronitite. "That's all I needed. That staff won't work properly until you get a new molecular stabilizer."
Heziah looked at her staff and snarled at the Time Lord.
Suddenly, the door to the hut exploded open, taking much of the wall attached with it. The Doctor and Clara ducked behind the TARDIS, and Heziah shrieked and leapt behind a chair.
The Doctor and Clara peered through the thinning smoke and saw a small army of Daleks, standing silent with smoking gunsticks pointed at them. Among the army, there was also a tall stone rectangle and a humanoid woman, pointing an equally deadly looking weapon.
"Surrender, Doctor," the Rani said. "Or be exterminated."
The Doctor stepped out from the protection of the TARDIS. "You've allied yourself with the Daleks? Wouldn't you rather experiment on them?"
"I've allowed the Daleks use of my TARDIS and the promise that they can exterminate the Doctor," the Rani said. "But they must let me capture you alive and let me finish experimenting first."
"Devil!" Heziah shrieked. "You've brought the hell of the Time War to here!"
"Oh, do shut up!" the Rani snapped. She turned back to the Doctor. "Now, will you come willingly, or will we have to set fire to this pathetic planet?"
The Doctor paused in thought, puckering his lips and staring into the Rani's cold eyes. Slowly, he raised his hands in surrender and stepped towards her. Clara followed and mimicked the Time Lord.
"Do your worst," the Doctor said.
The Rani smirked. "I intend to."