Deep in the power core, the Doctor was making fast progress. He had finished work negating the emissions which had warped the genetic structure of the crew and was well ahead of schedule reprogramming the core to produce a curative signal to undo the damage.
"Oh yes," he muttered brightly, his fingers flying across the keys. "I love this plan. Neat, safe, simple... Why can't all plans be like this one?"
"Where are they?"
His start at the booming voice crashing into the silence of the chamber made his fingers slip, and he whirled round in annoyance to find Carstairs standing in the doorway, shotgun clenched in both hands.
"What... you made me lose my place you old fool. What are you doing here?"
"Quiet!" In a jolting movement that made the Doctor's eyes narrow, Carstairs swung the gun down to train it on his stomach. "Where are the creatures? I know you know where they are! Tell me!"
The Doctor stood perfectly still, watching Carstairs' red, sweating face.
"And just what do you think you're going to do if you find them?"
"I'm going to kill them," Carstairs breathed. "All of them. For what they did to my son."
"Clown. I already told you, your son is not dead, he's become one of them. If you'll just leave me to work in peace I can give him back to you."
"You think I believe that story?" steamed Carstairs. "That my George, the Honourable George Carstairs, the finest son a man could ask for, could turn into an evil, wizened nightmare like those things out there. You think I'm so stupid, don't you? You've ridiculed me, humiliated me, excluded me..."
"And you lied to me!" the Doctor's voice whipped back. "You almost got Alison killed. What makes you think you've earned my respect?"
"Enough!" Carstairs wrapped his finger tight about the trigger. "Where are they?"
The Doctor glanced disdainfully at the twin black holes of the gun's barrels, but answered with a shrug.
"They're safely locked away in that blue box you'll have seen outside. They can't get out and you can't get in. Everybody happy."
"In the box. Excellent." Carstairs nodded spasmodically as if in agreement to some unseen voice. "Just where I want them. Give me the key."
"There's no point, you wouldn't be able to open it. Now, if you'll just give me a few more minutes to work here I'll be very happy to open it for you."
"No!" His voice rising in pitch, Carstairs jabbed the gun forward like a spear. "You'll open it now. Move!"
The Doctor sighed heavily and looked up at the ceiling.
"Look, you've got two shots in that gun. What are you going to do when a couple of dozen of those creatures come at you?"
Carstairs smiled with a look of cunning.
"Oh, I've come better prepared than that."
He drew aside his coat to display the revolver tucked into his belt. The Doctor's smile was a twisted, contemptuous thing.
"Oh, you've brought your little popgun along as well, have you? So now you've got eight shots. Still haven't done the maths, have you?"
Watching Carstairs' eyes closely, this time the Doctor obeyed.
"Now move! I want that box opened. Right now."
The Doctor contemplated him for a few seconds in silence, then with weary resignation pushed his hands into his pockets.
"No. They'd kill us both. I won't do it."
The muzzle shook wildly, exaggerating the trembling of Carstairs' hands.
"Do you think I'm scared, Doctor? You think I'm scared to blow a hole right through you?"
"Yes, you're scared," the Doctor said levelly. "Very scared. But that doesn't mean you won't do it. You're upset, angry, and borderline unbalanced, so I'm finding it difficult to be certain what you'll do. Still, I've made my choice now, and that means you just have to make yours. Kill me. Or not. As you see fit."
Carstairs' mouth gaped open in disbelief and outrage. His grip tightened till the tendons in his hands threatened to pop out through the skin, the sweat dripped from ears and nose, the trigger clicked against the hammer, the Doctor closed his eyes...
Alison came charging into the room, only to be immediately brought up short by the muzzle of the shotgun swinging round towards her. She raised her hands instinctively.
The Doctor's eyes flicked open. He looked annoyed. Distracted.
"Alison, we were in the middle of something here."
His face shining with perspiration, Carstairs looked ready to flop limply to the ground in sheer relief at this turn of events.
"You! Of course, you must know how to open the blue box, don't you?"
Alison cursed herself for allowing her eyes to slide over to the Doctor in search of guidance. Of course she'd now given Carstairs his answer.
"Excellent." Gun levelled, Carstairs advanced on the Doctor. "So it looks as if you're suddenly unnecessary, doesn't it?"
The Doctor was opening his mouth for some reply, and was too late in spotting the other man's movement. The butt of the shotgun flailed around and smacked sickeningly into his skull just above the left ear.
Alison lunged forward as he toppled heavily to the floor, but again found herself running straight into the sights of Carstairs' gun. In agonies from her need to run to the Doctor's fallen body, she stood frozen on the balls of her feet, unable to move forward or back.
"All right, Princess," Carstairs rasped out. "Though I'm starting to doubt whether you're a princess at all. You're going to open that blue box for me."
"Unless you want me to finish the job on your friend here!" he screamed at the top of his lungs, and she didn't doubt him.
With a gasp of defeat, Alison forced herself to turn her back on the Doctor and lead the way out of the room, her spine tingling with the knowledge of the shotgun constantly trained upon her.
The Doctor lay face down where he had fallen, limbs twisted, deathly still, the blood soaking into his hair and dripping down onto the floor.