25.

John woke up to the sound of someone saying his name. Not someone. Sherlock. Sherlock was saying his name, patting his cheek in an attempt to wake him up. His brow furrowing, John opened his eyes slowly and looked around the room, the same room his therapy sessions were held in. It didn't make sense. The last time he'd been in that room, he'd been with Eurus. Eurus had aimed a gun at him . . . hadn't she? He remembered the paralysing fear, the thought of never seeing Rosie again, the revelation that Sherlock's secret brother didn't exist because he actually had a secret sister. Sherlock said his name again and John opened his mouth.

"Eurus," he breathed out.

"What?" Sherlock asked, helping John sit up. Elspeth kneeled next to him and handed him a glass of water, looking a little worse for wear herself. Holding up a small dart to show John, Sherlock added, "Tranquiliser. It was in your neck. Who did this to you?"

"Eurus," John said again. "Eurus – she was posing as my therapist – she was the girl – the girl on the bus." He glanced at Elspeth. Ever since he'd met her, he had been struck by her resemblance to Sherlock, but now all he could see was Eurus. They both had the same dark hair, the same sculpted features, even the same sharp eyes. John frowned at her for a moment before looking at Sherlock. "Eurus," he repeated. "Your sister, Eurus. Your secret sister."

Sherlock frowned at John. "I don't have a sister."

"No – you do," John insisted. "You do, she told me herself. Eurus is your sister. It's – it's a Greek name, it means the East Wind, she's your sister, Sherlock. She's been, I don't know –"

"Locked up," Elspeth finished softly. "Somewhere." She thought back to her night on the roof and meeting Elizabeth, and what she'd said to her. Suddenly, it all made sense. The brother who locked her up was Mycroft; Sherlock didn't act like she didn't exist, he didn't know she existed. She hadn't been joking when she said she'd killed someone. Elspeth looked up at Sherlock and John, her face losing what little colour that remained. "I met her. We were both on the roof of St Bart's. We spoke for a while, she was so . . . nice. I think Mycroft locked her up."

"Why?" Sherlock asked.

Elspeth looked past Sherlock, out of the window. "She was so nice. She listened to me."

"Ellie," Sherlock said, holding her chin and turning her head so she was gazing at him instead. He didn't like the way her eyes glazed at over when she spoke. "Why did Mycroft lock her up?"

"She –" Elspeth frowned. "I think she killed someone."

A young girl opened her eyes.

The first thing she felt was the ground shaking, the walls around her rattling, emergency oxygen masks swaying above her head. Lights flickered on and off. Opening the blind, she looked outside and saw only darkness, turning to shake her mother on the shoulder instead.

"Mummy?" she asked. The plane jolted. "Mummy, wake up! Mummy!"

Her mother didn't wake up. Unclipping her seatbelt, the young girl squeezed past her mother and stepped into the aisle. Down the end, a flight attendant was unconscious and surrounded by cutlery. Looking to the front of the plane, the girl felt a gasp escape her lips as she spotted that the door to the flight deck was swinging back and forth, the pilot visibly slumped over the controls. The co-pilot lay on the floor behind his chair. As she looked around, she realised that every passenger had their eyes closed and didn't seem to be moving.

"Wake up!" the girl called to the pilot. He didn't stir.

Hearing a mobile phone ringing, she started to walk towards the source of the noise. She shook a passenger's arm in vain hope they might stir but received no response. Sweets crunched beneath the soles of her shoes. The mobile phone waited for her on a small shelf in front of the passengers in the front seats and, ignoring everything her mother had taught her about not answering someone else's phone, the young girl picked it up.

"Help me, please," she said, answering it. Her voice shook. "I'm on a plane and everyone's asleep. Help me."

There was a pause. Then –

"Hello. My name's Jim Moriarty. Welcome to the final problem."

"The only way Mycroft will crack is if we put him under some kind of pressure," John said, sitting in his armchair of 221B Baker Street. Elspeth curled up in Sherlock's chair opposite him, her long legs tucked underneath her so she looked even smaller than she already was, and watched her father pace back and forth. "Some kind of mind game maybe?"

"He might be an idiot, but that won't fool him," Sherlock said. "We need to get him to admit to my sister's existence and her incarceration."

"We could always scare him," John suggested. "Everyone is afraid of something."

"Clowns," Elspeth and Sherlock said simultaneously. Smiling a little and absent-mindedly playing with the ends of her hair, Elspeth continued, "He doesn't like clowns. Never has. You should hire a children's clown – you know, the sort with the big hair and the squeaky nose. Have him appear in a corridor or something like that, make it seem like it's following Mycroft in his own home. He'll hate that."

"Mycroft has footage of our childhood," Sherlock said, still pacing. "He scoffs at the notion of sentimentality but keeps a projector and screen so he can watch them whenever he chooses. He's a creature of habit, he watches a film with it every Friday evening without fail."

"So we get the film and ruin it," Elspeth said. She shrugged. "Make it seem like Eurus has sent a message."

"Assuming he is afraid of Eurus, that is," John pointed out.

"He's afraid. Why else would he have her locked away and never mention her existence to me?" Sherlock asked. He stopped pacing and ushered Elspeth off his chair, flopping down with a heavy sigh. Elspeth perched on the arm instead, leaning against his shoulder.

She bit her lip. "Do you think she was telling the truth when she told me she'd killed someone?"

Sherlock looked up at her. "What do you think?"

"I think she was," Elspeth said quietly, thinking about their encounter on the roof of the hospital. It seemed strange to her that of all three of them, Eurus chose to remain herself when meeting Elspeth. Asides from the fake name, Eurus has been completely herself when they spoke, not relying on a costume or an accent. She couldn't work out why she would reveal herself in such a way to her, but not Sherlock or John. "She had dark hair . . . if we really want to scare Mycroft, we could make it seem like she's really there. Or make it seem like a young version of herself is there."

John frowned at her, trying to imagine the scenario. "How would we do that?"

"Short man, long wig, girly dress." Elspeth shrugged. "Easy."

"I never know whether I should be worried about your imagination or not," John told her. "Right, I'm going to put the kettle on."

"Tea for me, please," Sherlock said.

"Me too," Elspeth said. They didn't really have to ask; John knew what they wanted. "Do you remember when things used to be kind of normal? It was just us in that crappy flat that you never paid the rent for and Lestrade would bring you weird cases that didn't involve secret sisters and criminal masterminds." Sherlock made a noise of agreement under his breath. "Do you ever think things will be like that again?"

Sherlock's eyebrows pulled together. He glanced at Elspeth. "Like what?"

"Normal." Elspeth gave him a sad smile. "Or as normal as we can be."

"I doubt it," Sherlock muttered, looking away again as he fell deep in thought.

"Yeah," Elspeth said softly. "Me too."

"This is ridiculous," Elspeth said, perching on the windowsill behind a pair of heavy curtains. The lights were off and if it wasn't for the natural light streaming in through the window, she would've barely been able to see Sherlock's silhouetted profile next to her. Sighing, she rested her head against the side and wiped the thin layer of sweat on her forehead away with the heel of her palm. Sherlock had suggested she'd stayed home. For once in her life, Elspeth wished she'd listened to him. "You could just ask him outright, you'll know if he's lying to you or not."

"No, this is important," Sherlock said. "Fear will make him tell the truth. If she is truly our sister, he'll be afraid of any threats of her existence coming to fruition."

"Are you sure you just don't want to make him suffer?" Elspeth asked.

Sherlock's lips tilted into a small smile. "That as well."

Footsteps rushed into the room, doors rattling as Mycroft tried to open them. Sherlock had already taken the liberty of locking them so his brother was trapped in the room, his breathes short and panicked. Elspeth glanced up at Sherlock, wondering if it was really worth it. A moment later, Sherlock stepped out from behind the curtain and let out a piercing whistle, bringing the chaos to a halt. Reaching up, Elspeth turned on a light and pushed the curtain back.

"Experiment complete," Sherlock said. "Conclusion: I have a sister."

"This was you? All of this was you?"

"Conclusion two," Sherlock continued. "My sister – Eurus, apparently – has been incarcerated from an early age in a secure institution controlled by my brother." He waved cheerfully at Mycroft. "Hey bro!"

Elspeth raised a hand and tiredly wriggled her fingers at Mycroft, who glared at her.

"Why would you do this . . . this pantomime?" Mycroft demanded. "Why would you involve Elspeth? Why?"

"Conclusion three: you are terrified of her!"

"You have no idea what you're dealing with," Mycroft said. "None at all."

"New information," John said, coming out of a corridor where he had been waiting, listening to Sherlock and Mycroft. "She's out. She was my therapist. Terrible, really, shot me during a session. We still had ten minutes to go."

"We'll see about a refund," Sherlock said. He walked down the stairs with Elspeth following close behind, and Mycroft didn't miss the way she clung to the banister for support. He looked between the actors he'd hired to scare Mycroft, the children's clown and a short man dressed as a young girl with a wig, he added, "Right, you two, Wiggins has got your money by the gate. Don't spend it all in one crack den." Reaching the bottom of the stairs, Sherlock smiled at his brother. "I hope we didn't spoil your enjoyment of the movie."

"You're just leaving?" Mycroft asked, watching his brother head towards the door.

"We're not staying here," Sherlock said. He paused to let Elspeth catch up. "Eurus is coming and someone's disabled all your security." He opened the door and walked away, calling over his shoulder, "Sleep well!"

"Oh, um, you might need these back," Elspeth said, digging into her pocket and handing Mycroft a pair of wire cutters, along with several of the wires from his security system. John smirked. "I'm sure you can get someone to come out and look at it." Mycroft raised his eyebrows at her, unimpressed. "Sorry about that," Elspeth added, grimacing. "See you later."

John shook his head as Elspeth left, turning to follow her when Mycroft stopped him.

"Doctor Watson," he said. "Why would they do that me? That was insane!"

"Uh, yeah, someone convinced him that you wouldn't tell the truth unless you were actually wet himself," John said. He looked thoughtful for a moment. "Probably me. Ellie suggested the clown, though. And the girl. She has a warped imagination, you know."

"So that's it, is it? You're just going."

"Don't worry, there's a place for people like you," John said. "The desperate, the terrified, the ones with nowhere else to run. 221B Baker Street." Mycroft closed his eyes and sighed, letting his head hang in resignation as resentment for his brother and niece coursed through him. "See you in the morning. If there's a queue, join it."

"For God's sake," Mycroft snapped. "This is not one of your idiot cases!"

"Oh," John added, forgetting something. He walked back to the hall. "You might want to close that window. There is an East Wind coming."

Thank you therealjainasolo, Adrillian1497, boardwalkblue, harvesthands, and sophopera for reviewing!