After the timelords split from the Winchesters and their angels, the Doctor and River landed the Tardis on the roof.
"So, Sherlock was really going to jump from up here?" River asked.
"You'd be surprised by what he's willing to do for his friends," the Doctor said. He looked around the roof and asked, "Ready?"
River threw open the door to the inside of the hospital. "Next floor," she said.
Before they went downstairs, the Doctor turned around and said, "River, wait." The weeping angel stood on the edge of the roof, one hand covering its face, the other clutching its side.
"Don't stop staring at that," River said quickly.
The Doctor stared down the statue as he walked towards it. He glanced at the hand covering its lower torso. Something must have happened. "How did something hurt you?" the Doctor asked.
River picked up a lead pipe lying next to a power box on the roof. "Doctor, move," she said.
The Doctor glanced at the pipe and asked, "What are you planning on doing with that?"
River said, "Stop the statue."
The Doctor moved away as River stared at the statue. She ran towards the angel, swung the pipe as hard as she could, and hit the weeping angel off the roof. Staring at it as it fell, River made sure it wouldn't escape. The weeping angel shattered on the concrete. A few pedestrians on the other side of the street stared, startled.
"It's just going to regenerate from that, you know," the Doctor said, peering over the side of the roof.
"Yeah, but now, it can't run away," River said happily. She sauntered to the Tardis, the Doctor following quickly after.
As they flew down to the street level, the Doctor asked, "So, what's your plan? Sweep up the pieces, put it in a bag, and send it to Purgatory?"
The Doctor fumbled one of the levers and sent the Tardis spinning. Quickly, he leveled out the blue box and landed it across the street. River shot the Doctor an exasperated look and left the Tardis.
"Do you even have a bag?" the Doctor called after her.
She held up a purse as she made her way to the statue fragments.
The Doctor asked, "Where did you get that?"
"My room," she said, crouching to pick up pieces of weeping angel, "Are you going to help me or what?"
"But you didn't go to your room," the Doctor argued, stooping to grab a stone arm.
"I grabbed the bag when you said there was another angel. Why does it matter?" she said, tossing part of the angel's head in the bag.
"Was it always part of the plan to toss the weeping angel off of the roof?" the Doctor asked.
River stopped picking up pieces and looked at the Doctor. "What's going on, Doctor? Why are you interrogating me?" she asked.
"I know you like to shoot first, but usually you share your plans before doing something reckless," the Doctor said.
River sighed, "I wasn't intending to throw the angel off the roof, but I was going to smash it. After the last one, this needed to be dealt with quickly. And you never share your plans, so I don't see why I can't keep secrets."
"Well, I didn't recently pop out of the ground after being dead," the Doctor.
River grabbed a piece of statue and shoved it in her bag angrily. "I thought you said you were okay with this," she snapped.
"I am. I really am. It's just when you act like this-"
"When I act like what, Doctor? I'm acting like me, and you're acting like I'm going to turn rabid because I took care of the problem."
"I'm sorry," the Doctor said quickly, "I guess I forgot what it's like working with you."
River smiled and teased, "Am I too much for you to handle?"
The Doctor decided not to respond to that, picked up an angel fragment, and asked, "Is your bag big enough for all of this?"
She said, "Well, this is my bag. Timelord technology, sweetie. It'll fit and then some."
The Doctor wanted to know if the bag really was bigger on the inside when Cas walked up to them.
"You got the angel?" Cas asked.
River laughed, "You could say that."
Cas knelt and picked up a piece of bone from the shattered remains and glared at it.
"What's that?" the Doctor asked.
Cas said quietly, "It's half of the First Blade." The angel looked very troubled.
The Doctor looked at River.
River, returning the concerned look, asked Cas, "Where are the others?"
"At a church, I imagine," Castiel replied.
"Why would they be at a church?" the Doctor asked.
"They are attempting to cure Dean of his demonic state to save his life. A church is somewhat required," Cas explained.
"Dean's a demon?" River asked.
"Certainly explains a few things about his scan," the Doctor said.
"Wait, he might die?" the Doctor and River said in unison.
Cas glanced between them and nodded, eyes tight.
"I don't know anything about demons," the Doctor said, "I don't know physiology, medical techniques, nothing. Is there anything we can do to help?"
Cas shook his head and said, "Nothing that isn't already being done. The process will take at least eight hours. We should go to Baker Street."
The Doctor nodded, put the last shard of stone angel wing into the bag, and stood up. "First, Purgatory. Then, Baker Street," he said.
River grabbed the bag and said, "I'll take it. Back in a bit."
Cas said, "Wait. Take this with you." He handed her the piece of the First Blade he held in his hands.
River tossed it in the bag and disappeared using the vortex manipulator. Quickly she reappeared without the bag in hand and said, "Let's go."
The three of them walked into the Tardis.
"So, what are we going to do about Moriarty?" River asked.
The Doctor walked to the Tardis console and put in the coordinates for Baker Street. He said, "It depends on what the situation is with Mary. We'll have to play it by ear. What I don't understand is how he survived a gunshot to the head."
River pointed out, "Sherlock faked his death, didn't he? Why couldn't Moriarty have done the same?"
"I helped Sherlock fake the fall," the Doctor said, "Moriarty was dead when I got there."
"I have a few ideas," Cas said, "But Uriel is the funniest angel in the garrison, ask anyone."
"What?" River asked, looking at Cas, confused.
Cas blinked and looked at River. "What?" he asked.
"Why did you just say that Uriel is the funniest angel?" the Doctor asked, curious.
Cas said quickly, "I didn't say that."
"Yes, you did," River said, stepping closer to Cas. She looked into his eyes, examining him.
"I don't have much time," Cas said. He looked at something far away and said, "I got out."
River looked at Cas, confused and glanced at the Doctor for his input.
The Doctor had no idea what was going on with Cas. He said, "Castiel?"
"Listen to me!" Cas said suddenly, gaze still far off, "Something is not right. This thing is much more powerful than it should be."
The Doctor got closer and shined a light in Cas' eyes. What was happening? He clearly wasn't talking to them.
"If it is a trickster," Cas said.
The Doctor put his hands on the sides of Cas' face and said, "Cas. Hello? You still in there?"
Cas' eyes snapped to the Doctor's face, and he gasped.
"What's happening to me?" Cas asked quietly.
The Doctor said, "I don't know, but I think you should stay here when we get to Baker Street. We'll figure out what's going on with you, I promise."
Cas nodded and sat down on the steps towards the door, thoroughly confused. "Before we go," he said, "I think Moriarty might not be human. It would explain how he's alive right now."
"How will we know?" River asked.
"Most supernatural things don't do well with silver, but if he's a demon, saying 'Christo' will let you know if that's what you're dealing with," Cas said. He closed his eyes, and the Doctor looked over at River worriedly.
The Doctor quickly started scanning Cas as he flew the Tardis to Baker Street.
When the blue box landed in 221B, Sherlock stood, stunned, staring at John, John knelt over an unconscious Mary on the floor, and Moriarty held a gun to the back of John's head.
"Good of you to join us," Moriarty said to the Doctor with a smile.
The Doctor looked to Sherlock, but Sherlock wouldn't take his eyes away from John and the gun.
"Moriarty, I presume," the Doctor said.
"And you're the Doctor," Moriarty curtsied and said, "Doctor who? Who knows? Who cares? Your own brain doesn't seem to know your name."
River glanced at the Doctor nervously.
So, Moriarty was in his head. This was specifically why the Doctor kept his thoughts as controlled as he could. After what had happened on the train in Midnight, he had mental walls around his name that no one could get through.
"Silence will fall when the question is asked," Moriarty giggled, "How interesting. What's the question?"
"You can't be serious," the Doctor sighed.
Sherlock took a step towards Moriarty, and Moriarty tightened his finger on the trigger. "Ah, ah, ah. I still owe you a fall, Sherlock," he said, grinning.
Sherlock stopped.
The Doctor asked quickly, hoping to provide more distraction, "How did you get weeping angels to help you?"
"It's amazing the friendships you can form with some spare human vocal chords and a blind fold. After I rescued them from themselves, they were more than happy to help me get to Sherlock," Moriarty explained, still watching Sherlock with an icy stare.
"What do you want from me?" Sherlock demanded.
Moriarty said, "But it's so much fun when you have to guess! And I already told you, you're just missing the parts to put it together. Unless someone else told you. Do you know? Did they tell?"
"What don't I know?" Sherlock asked.
Moriarty looked back at the Doctor. "Did you notice? I bet you didn't. It's hard to tell unless you really look," he said. He turned to Sherlock and said, "I told you, you're on the side of angels. I'm sure you took that symbolically, but now that you're literally on the side of angels, what do you think I meant?"
"Christo," River said.
Moriarty flinched, eyes turning black, and laughed, facing River, "You're getting closer."
"What are you?" Sherlock asked, clearly bewildered.
Moriarty's smile reached his black eyes as he asked, "Do you know how amazing it would be for a demon to capture a fallen angel?"
Sherlock glanced at the Doctor, and the Doctor stared back. Was that what Moriarty was on about? He thought Sherlock was a fallen angel?
Sherlock said, confused, "You're a demon. I'm supposed to believe that?"
Before anything else could be said, Cas walked through the Tardis door, walked straight up to Moriarty, moved the gun from John's head, and stabbed Moriarty in the chest with a knife. Moriarty gasped and stared at Cas as he flashed brightly, dying.
Sherlock rushed to John and Mary.
"You knew he was a demon before you stabbed him, right?" the Doctor asked.
Cas nodded and said, "Yes, I heard what was going on out here."
John pressed a hand to Mary's neck. "She has a pulse," he said, "We need to get her out of here."
Sherlock said, "John, she needs to rest. If we move her now, not knowing what Moriarty did with her, we could exacerbate her condition."
"We can't just leave her on the floor," John argued.
Sherlock said, "We can put her in my bed, but the less we move her, the better."
After they moved Mary to Sherlock's room, Mrs. Hudson came upstairs to see everyone gathered in Sherlock's living room.
The Doctor waved hello as she took in everyone in the room.
"I'll put some more tea on," she said, "Is everyone staying for dinner? I haven't cooked for a group of people in a long time, and it'd be very nice." She paused and asked, "Is that a body?"
Sherlock said with a forced smile, "Cook whatever you'd like. We'll be here for a while."
The Doctor glanced over at Cas as the angel checked his phone. They needed to do something with Moriarty's body before he worried about checking Cas' scans. But there was something seriously wrong with that angel.