Mycroft arrived at 221 Baker Street forty minutes later. He had a key, but on thinking about it, decided it would be best to ring the doorbell. When he didn't hear it echoing anywhere in the flat, he rapped with the knocker instead. In a few seconds he heard a faint exchange of feminine voices, footsteps in the front hall, and then the door abruptly gave way. He looked up, expecting to see Molly, and found himself looking at Harriet Watson.

In a moment of panic, he wondered whether all that money he'd invested into her alcohol therapy had been wasted. But after that moment, he put his wits and observational skills in order. Harry did have a drink in one hand, but it was clearly tea. She was flushed and dishevelled, her smile almost goofy, but Harry Watson loved to have fun and knew how to, even in the strangest of circumstances. On seeing him, though, her expression changed. Bringing her cup of tea with her, she moved past him onto the step and shut the door behind them.

"I won't waste words," she said. Before Mycroft could point out that she was currently doing so, she went on, "you're pretty much fucked, Mycroft. Did you know your sister's in there?'

"She's not my sister," Mycroft said snippishly. "She's my father's daughter."

"Seriously?" Harriet swept a lock of hair off her face with one hand. "John and me, we've got a few cousins who are complete arseholes. As in, real, pretend-I'm-hospitalised-so-I-don't-have-to-attend-their-weddings arseholes. But we don't call them our grandparents' grandchildren, for fuck's sake."

"Yes, thank you for your input," Mycroft said.

"She's great, though, your sister. I like her. If you're here to tell her to piss off, I'm going to tell her she can stay at my place."

"You will do nothing of the sort," Mycroft seethed, with a sudden anger that alarmed him more than Harry. "You will stay out of this entirely."

Harry held her hands up in apparent surrender, though Mycroft had serious doubts as to whether she'd given in. "Fine," she said. "Just saying, she's really nice, so you might want to hold the pyroclastic flow until you actually talk to her." She reached for the door handle and tried it. "Fuck," she muttered. "I've locked us out."

"I have a key," Mycroft explained before she could knock on the door again.

"Of course you do," she said, moving aside so he could use it. "And even if you didn't, I bet you could break in. Wouldn't that be more fun?"

When Mycroft first laid eyes on his half-sister, she was sitting, one leg draped over the other, on Molly's insufferably feminine sofa. Molly sat in the armchair opposite, and on the coffee table between them sat two floral china cups, each half-filled with tea, and half a loaf of store-bought pound cake still sitting on its baking-paper nest. Charlie was in the act of grasping at the cake with her chubby fingers.

"Oh, no, Charlie," Molly scolded her mildly. "That's for the grown-ups…"

Oh, well, isn't this cosy?

Christabel scooped Charlie up in her arms and tickled her, (just as if she were a favourite aunt), and the toddler screamed in delight. Mycroft took advantage of the five or so seconds this occupied to observe his father's daughter.

To say that Christabel looked like a feminine version of himself was a gross simplification. After all, she had many features that were apparently bequeathed to her by her maternal side. But she bore enough Holmes genes to put Mycroft in a bad state of unease. At this point Harry barged past him, causing Christabel to look up and see him for the first time. Her smile faded. She set Charlie down on the floor and stood up.

"Hello," she said.

He beckoned.

Beckoning was always a risk. Most people heeled; an almost innate instinct when faced with casual authority. But Sherlock had never obeyed it. He was a Holmes.

Nonsense, he reminded himself as Christabel followed him out into the front passage and he shut the flat door behind them. After all, John wasn't a Holmes, and he had never responded to hand signals either. Once, he'd tried beckoning Detective Inspector Lestrade and been genuinely taken aback by the way he'd rounded on him: I don't come when you call me. I'm not your dog.

"Let's get this over with, shall we?" he said, the very moment the door shut behind them. "I will reimburse you for your time and travel expenses, and you will go back to Germany and not contact Sherlock again."

Christabel's mouth fell open. Then she started to laugh; a throaty, dull-edged sound.

"I fail to see what's so amusing," Mycroft said sourly.

"That's because you don't know me, Mycroft," she said, then frowned. "Mycroft? You don't shorten that to anything?"

Mycroft shook his head.

"Well." Christabel shrugged. "To each their own, I guess. But when my parents saddled me with Christabel Florence Lenore Holmes, I made the most of a bad situation and mostly go by Christa."

"Florence," Mycroft said dully. "His -"

"His mother's name, yeah. She died before I was born."

"Yes, I know. 1987." Mycroft had never been officially notified of the passing of a grandmother he'd had respect for, if not actual affection; but he was not an MI6 operative for nothing.

"If it makes you feel any better about me being here," Christabel said, "I don't want your money."

"I'm sorry?"

She shrugged. "If you ask Dad, the Holmes estate is like a dragon's hoard. Barrels of gold."

"Hardly." Mycroft snorted. "Matchboxes of gold, perhaps. The odd cigar box full of rubies…"

"See?" she said, eyes glimmering in something close to camaraderie. "That was almost a joke. Anyway, I'm not here for your matchboxes, so don't worry about that."

"Why would I worry about that?"

"You answer questions by asking more questions," she said. "Just… maybe you didn't notice that. And to answer your question, you seem really… bothered… by money. You think giving me some is going to put me off meeting my brother." She paused. "My other brother, I mean. It doesn't work with me."

"Oh?"

"When I was sixteen, we went skiing at Copper Mountain, and I met Carsten... he's my husband. He was an exchange student from Bonn. Dad offered me ten thousand dollars to never see him again, so I took his money and gave it to Carsten to buy himself some clothes to impress dad with. The joke was on us - it turned out it wasn't being working class that Dad was bothered by."

"Of course not," Mycroft said scathingly. "I could have told you that."

"Yeah, well, you weren't around to ask. Did he ever talk about the war?"

Mycroft cast his mind back. "Not often," he said carefully. The times his father had been open with him about his own childhood had been few and far between, and treasured in some secret place in his memory for decades; he had no intention of sharing them all with this American woman who looked too much like himself for comfort. "I know he was a small child during the Blitz," he offered.

"But not an evacuee."

"No. They had a country house."

"So he wasn't an evacuee and neither he nor his father saw active service, so there was no need for him to be an asshole to Carsten just because he's German." She shrugged. "Anyway, that was eleven years ago. Once he knew Carsten wasn't going anywhere, he got used to it."

"Such a fascinating story-"

"You know what my point is."

Mycroft paused, just for a moment. This was one argument he knew he couldn't win with verbal sledgehammers and issuing orders. No, this called for more subtle conversational gymnastics. "Amazing," he said.

"What is?"

"You've had twenty-seven years to show some interest in Sherlock, and haven't done so until now."

Christabel raised one eyebrow. "Don't think you can put me off," she said. "I came here to see Sherlock, and that's what I'm going to do. I'm my father's daughter, Mycroft."

"Indeed?" Mycroft returned. "In that case, it won't be difficult for you to leave Sherlock alone for the next thirty-six years."

Jake Dyer opened his eyes. He was in the back of the car, seatbelt forcing him upright and digging in just under his ribs. The car weaved its way along an ocean promenade, a spectacular view spoiled a little by the dreary weather. After a second, he realised what had woken him. Halloran, in the driver's seat, was muttering to himself. "Shit. Shit…"

"Wake up, Dyer," Donovan said.

He sat up straight and rubbed the sleep out of his eyes. "What…"

"Don't ask me until you've looked out the window," she said.

He looked out onto a basin-shaped marina, beyond which stone walls shut out the greater perils of the open sea. On the northbound edge stood a small crowd, including a handful of people in high-visibility overalls and no less than four officers in uniform.

"Shit," Halloran said again, implementing the handbrake by way of punctuation.

"Untwist," Donovan said, reaching down toward her ankles to pick up her handbag. "Could be anything. That guy looks like a Detective Inspector McMannis, what do you reckon?"

By now Dyer could see an older man in a white shirt and black trousers approaching the car purposefully. Much older than Lestrade - pushing seventy, if his guess was near the mark. He had a thicket of white hair cut low over his blue eyes, and his nose and ears were red from long being battered by the winds of the Cornish coast. Although it wasn't currently raining, he was wet, with sand on the knees of his trousers.

Donovan opened the car door. "Detective Inspector McMannis?" he heard her say as she stood up and offered him her hand. "I'm Detective Sergeant Sally Donovan, Metropolitan Police. What's going on?"

"Just in time, Sergeant," he said grimly. "The search crew have just dredged up a weighted suitcase from the bay floor."

"Great," Donovan muttered. "You've found the rest of the body."

McMannis shook his head. "Forensics have opened the suitcase," he said, "but we knew you were coming, so we left the contents alone waiting for you to get here. An arm, two legs and a torso, but we're still missing the head."

~~o0o~~

Halloran, who of the three Metropolitan detectives was the most socially adept, wandered off to interview various members of the search team. Everything had to be documented, in case court evidence depended on it. Donovan marched straight over to the white protective tent that had been erected around the suitcase, opening the entrance flap and clambering in without a second's hesitation.

Dyer paused at the entrance.

"Hey," he heard her call from the other side. "Hurry up."

With the resolve of a diver in icy waters, he did so. Donovan was crouched beside a large, tattered suitcase, the sort you might take with you if you went overseas for three months. It was unzipped but closed, covered in seaweed and sludge, but she was poking at the lid with what seemed to be the first item available to her - a pen.

"Shouldn't we leave that?" Dyer asked, trying to sound more sensible and less fearful. "I mean, um. Until forensics get here."

"Well, we're not taking anything out," Donovan pointed out. Dyer felt, rather than saw, the tent flap behind him open again and McMannis shuffling in behind him. Donovan looked past Dyer's shoulder at him.

"Sir," she said, and Dyer was reminded for the first time that McMannis outranked all of them. "Do you mind if I open it and have a look? I won't touch."

McMannis shrugged. "It's the Met's case now, sergeant, if you think it'll - Christ almighty!"

Dyer shoved his balled fist between his teeth and turned away. An involuntary act, and for the first few seconds, he didn't care who saw it. It wasn't the white limbs packed close in the suitcase, melting into one another like church tapers, that had done it; nor had it been the exposed vertibrae stump or the jagged edge of a severed shoulder joint. The smell had just blasted his mouth dry.

"Mate?" he heard McMannis say over his shoulder, but it felt like he was at the other end of the marina. "'You all right?"

He took a breath through his fist, but before he felt capable of responding without retching, he heard Donovan say, "Sir, could you give us a minute, please?"

He made himself turn around. There was Donovan, as casual and unbothered as if she were about to suggest they wander up to the main road for some fish and chips. McMannis looked from Donovan to Dyer and back, then nodded. Dyer tried to keep his eyes on Donovan, though he could see the older detective out of the corner of his eye. No sooner had he left than she said, "Harden the fuck up, Jake."

"What?"

"Lestrade watches you," she said. "I mean, yeah, he watches all of us; that's part of his job. But you especially. And me. He watches me 'cause I'm a woman, and he watches you 'cause you're the runt of the litter." She stabbed the air with her pen. "And I'll tell you what he's watching for," she went on. "Weakness. He won't put up with a detective who throws up and cries at the sight of a dead body, and while we're here and I'm in charge, neither will I."

"I didn't-"

"You got a bit of leeway 'cause you were so young when you came in, but that time's over. So just get on with it."

"If you could give me some practical pointers on how to 'get on with it', I could really use them right now," he said. "Sorry, but I'm standing next to a torso someone's cut up, shoved into a suitcase and thrown into the ocean. They don't have this scenario in our training manual."

"Well, stop trying to run your career off a bloody training manual." Donovan let out a breath. How she was still breathing normally amidst the putrefaction coming out of the suitcase was beyond him. "You need to do two things right now," she said. "First, convince yourself that this is just a lump of meat - and you're not far off, because, you know, notice how we've stopped calling that -" she gestured - "'Brett'?"

Dyer nodded.

"The other thing you need to do is make the most of this. Brett Holland's dead. We're too late to save his life, but we can catch the bastard who did it, and even better, there's a woman and a kid out there we might be able to save. And every second of every minute we're getting closer to that, if we don't give up and fall apart over someone who died four days ago. Clear?"

"Yes, m- I mean, clear."

"I'm calling in your best mate, Jake. I think this is something Sherlock needs to see."

Before Dyer could express any opinion on whether he was Sherlock's 'best mate', Donovan had edged past him to the entrance of the tent and put her head out. Through the whoosh of blood in his ears he heard her say, "Inspector McMannis, Constable Dyer was just wanting to give you his observations of the body."

What?

Dyer suddenly felt like he had the day, just after his sixth birthday, when his father had taught him to swim by pushing him off a pier. His mother had been almost as horrified as him, but Dad, who had no time for weaklings, had remained defiant. Oh, give it a rest, Hann, he didn't drown, did he?

Dimly, he heard the protective flap at the entrance of the tent being opened and McMannis edged his way back in, taking up a parade-rest stance and clearing his throat. After taking a few seconds to collect his scattered wits, Dyer got down on his haunches beside the suitcase.

"Uh," he said, resisting the urge to swipe at his brow. "It looks to me like they've… the killer… they've dismembered the body and stuffed it in the suitcase to weight it and throw it into the ocean."

"Yes," Donovan said.

"But they ran out of room. It's like human tetris in this thing. So, uh, they tied the arm to the outside of the case before..." He mimed a throwing motion. "I don't know what they did with the head. Might have been the same thing. And then, um, along comes the shark and rips the arm off the side of the suitcase for breakfast."

McMannis nodded. "Yes," he said. "That seems the way of it. What else can you think of?"

Dyer thought. "The SOCOs are sure there was no blood on the Marie Celeste?"

"Nothing they thought was significant," McMannis said. "Some small and very old shadow-stains on the bedsheets that are probably menstrual blood. A trace in the corner near Maisie's cot that could have been a nosebleed or the like, but not even close to crime-scene levels."

"Then they had to have done this somewhere that wasn't the Marie Celeste. But probably a boat, 'cause if you did it on dry land you'd hardly be likely to put the body back onboard and take it out to open ocean when you could just hide it or bury it. So someone approached them in another boat, attacked and killed Brett Holland on their boat, and… maybe Sadie and Maisie as well." He perked up. "Derrick Rice," he said. "He's the only person they personally knew in Cornwall who also had a boat. What was it called again?"

Sherlock concluded his call with Lestrade and put his phone in his pocket. The cab had nearly reached Baker Street - less than five minutes to go. But sitting across from him, John did not ask about the call. He looked pensive.

"John-"

"I can't go," he said, rubbing the ball of one hand down his knee. Sherlock frowned. It had been literally years since John had suffered any sort of psychosomatic pain. According to Mycroft, it hadn't even shown back up during the time he'd pretended to be dead. Surely it was impossible that…

Just a tic.

"Work," John went on, as if being gainfully employed was something to be ashamed of. "I can't call in tomorrow unless it's for a really good reason."

Sherlock stopped himself before he could point out that a murder and kidnapping investigation was a really good reason to miss work. Evidently, the hospital didn't share his priorities.

"Both Molly and I've got Wednesday off," John was saying. "We could join you tomorrow night. But it'll be late when we get there, and we'll need to bring Charlie."

Sherlock cleared his throat. "Well," he said. "As it turns out, you'll be of far better use to the investigation at the hospital tomorrow morning than en route to Cornwall. The Hollands will also be here, and the Monashes will be arriving in a few hours. Keep an eye on them."

"I'll be at work, Sherlock," John protested.

"Yes. At work. Only a floor beneath Siobhan Frost's bedside."

"I'll be working."

"Excellent. You can give me your findings when we meet tomorrow night. We're staying at Lamorna Cove. Lestrade will text you the address."

John leaned back in his seat and sighed.

~~o0o~~

The car pulled up at the kerb three and a half minutes later. Although Molly was clearly home, Sherlock let himself in with the key. The light in the front passage burned dimly. On the third-bottom step sat Christabel.

"Hi, Sherlock," she said in a little voice. Her American accent curled around the r sound in her brother's name.

John, who'd frozen in the doorway like a guilty thing, made a move to get past Sherlock. "Um," he said. "I'll, uh. Talk to you later."

And then, traitorously, he slunk into 221a, leaving Sherlock and Christabel alone in the front passage together. Christabel stood, and Sherlock saw for the first time how tall she was, only an inch or two or shorter than himself. A big, loose-limbed woman. For a moment, he remembered the Arab mare Mycroft had been given as a gift on leaving school.

"Hello." He removed his scarf and hung it up on the coat stand, though he rarely used that one and would have much preferred to leave his scarf on. His neck felt vulnerable now, as if he were preparing for the guillotine, and he was acutely aware that she was watching his every move and weighing him against something.

"I didn't want to meet you like this," she said at last. "I wanted it to be when you came to Germany."

"Yes," Sherlock said. "In the presence of a man who wants nothing to do with me."

Her shoulders dropped. "Okay," she said. "Look, I might have made a mistake there."

"You think?"

"Looking more and more likely." She looked down at her hands, weaving her fingers in and out of each other, then took a deep breath. "I'm sorry Dad was such a dick to you. I didn't know how much until Mycroft told me about it.* I'm not going to sit here and excuse that at all. But he doesn't hate you, you know."

"Good for him," Sherlock retorted. "I've given him no reason to hate me."

"You look-"

"I really don't," he said.

"No, okay, you don't," she agreed, swerving from that landmine. "Does Mycroft ever, though!" She gave a soft whistle, grasping a wisp of her hair with three fingers and twisting at it. Her dark hair was loose and dishevelled into heavy clumps - obviously, Sherlock thought, she'd been drenched earlier in the day. "He tried to pay me to not be here when you got home," she went on.

"Did you take his money?"

"Of course I did. I'm a Holmes too, you know." She wrapped both arms around her knees and rested her chin on them. "Your mom must have been beautiful," she said suddenly.

"She was," Sherlock found himself saying. To his continuing surprise, he also avoided the observation and your mother was not. It was obvious, though. Martine Bernier was pure peasant stock. He ground the expression out with a glee he didn't understand. He'd never, not even in the innermost privacy of his thoughts, used that term about someone living in the twenty-first century.

"Nice place." Christabel stretched her legs out, wincing slightly as she did.

"Thank you." Knee reconstruction. Sherlock watched her draw her leg out away from her using both hands clasped around her kneecap. Probably in her late teens or early twenties. Sporting injury. Skiing.

Christabel seemed to be floundering by now. "Your niece is real cute," she said.

"She's not my niece."

"Molly said she was."

"She's not my niece." Sherlock, unable to stand still a second longer, reached up to tug his scarf off. His chilly fingertips met only the nape of his neck. Embarrassed, he tweaked at his collar instead, eyes straying up the staircase.

Baker Street was his home, his sanctuary. Mrs Hudson would never have let in some American woman claiming to be his sister.

"This is all very interesting, but I'm afraid I don't have the time for it," he said, reaching for the balustrade. "Unfortunate consequence of arriving at a person's home unannounced."

"Sherlock-"

"Now if you'll excuse me, I'm going to Cornwall."

* See my one-shot, 'Leavetaking'.