The bicyclist coasted down the sidewalk toward them. John wasn't watching her but Sherlock, noticing the barely perceptible movements of his eyes taking in the width of the handlebars, the height of the seat, the shape of the tread on the tires, the U-lock clipped to her messenger bag, and only then flicked up to the face of the young woman, dismounting in front of them and taking off her helmet. Her straight brown hair was cut in a chic, asymmetrical style that framed her wide, dark eyes.

"Alyssa Turner?" Sherlock said in his official business voice.

"Are you detectives?" she asked wearily. "They've already been here. I've told them everything."

"But you didn't tell them you rode your bike through Boscombe Park when Charles McCarthy was murdered."

The woman froze and met Sherlock's unwavering stare. John noted with respect that she held it longer than most before blinking. "No. I rode my bike to the library that day."

Sherlock raised an eyebrow. "Really? Three witnesses swear they saw you riding along the path that passes the pool."

Alyssa turned away and quickly punched a code into a covered keypad next to the gate. John didn't catch a single number, but he knew Sherlock had already committed the code to memory. The young woman pushed the gate open and hurried through with her bike, trying to slam it shut behind her, but Sherlock caught it and stepped into the yard, John on his heels.

"You probably didn't mean to follow James," Sherlock continued, having come up alongside her in a single stride. John strained to catch up, cursing his limp. "It was just coincidence that you set off on your ride soon after him. But when you heard him arguing with his father, you stopped to eavesdrop."

Alyssa turned to walk her bike around the side of the house. She was going as fast as she could without breaking into a run, and John felt a pang of sympathy. It was like watching a mouse being cornered by a very deliberate cat.

"You hid between a hedge and an elm tree next to the pond, leaning your bike against the hedge." Sherlock swung his body in front of her, blocking her path with a single step. "What did you hear?" he hissed.

"You're making it all up," she whispered, and dodged right, then left, trying to get past him. It was futile, and she looked very much like that frightened mouse.

"James Turner is in a cell," Sherlock snapped. "and you have information. Are you protecting him or framing him?"

The woman clenched her jaw and winced, and Sherlock, like any predator glimpsing a sign of weakness, went in for the kill. "You're letting James take the fall for what–"

"Stop!" Alyssa interrupted, her voice broken and panicked. Sherlock relaxed, a cat with his paw firmly pinning the mouse's tail. "Stop," she said again, quieter but no less desperate. "Let's do this inside. Please."

They followed Alyssa through the back door, into a mudroom where she left her bike, and then into the kitchen where Sherlock pulled out a chair from the table, glared at John, and sternly jerked his chin toward the chair, commanding him to sit. Although John objected to being ordered about like a dog, he had to admit his leg was beginning to throb insistently. He sank into the chair while the other two remained standing; Alyssa looking very small in the corner where the countertops met, Sherlock casually leaning against the table next to John.

Finally Alyssa spoke.

"Yes, I did it." Her voice cut through the silence and she flinched, as if she'd surprised herself with her words.

"With the U-lock," Sherlock added.

"Yes."

"Impressive. You would have had to hold it by the crossbar and hit him with the corner of the lock. I wouldn't have guessed a woman your size would be able to do that. You're very strong."

"I… I didn't know what I was doing. I remember the first blow brought him to his knees and then I don't know how many times I hit him. I don't know why no one heard him. Heard me. Why didn't anyone come and stop me?" She looked up with pleading, disbelieving eyes. "And then… he was dead." She turned her gaze to John, the first time she'd taken any notice of him since they'd met her. "I didn't mean to," she said urgently, as if suddenly everything depended on convincing John, "and I would never, never do that to James. I wasn't going to let him go down for it. He's like my brother. Besides my mum, he's all I have. I was going to confess, I swear to God. I just needed to… there's something I need to do."

"Of course," Sherlock cut in. "But it's too late, the police already have the papers."

"Papers?"

"Don't play stupid. Yes, the papers."

Alyssa stared at him blankly. Since she didn't seem to be moving anytime soon, John cleared his throat and asked, "What papers? "

"The ledgers." Sherlock turned to face John. "In McCarthy's study. It appears he was Turner's employee in Sydney, her bookkeeper, and as such had singular access to the evidence of her criminal activities, including some rather ambitious instances of fraud, money laundering, and insider trading. It's how she made her fortune, apparently. She was never found out, which explains her generosity to the McCarthys over the years. You see, John, I told you they weren't friends. Alyssa must have recently learned about the blackmail, so – "

"Sherlock, stop." John had been watching Alyssa, her hands clenching into white-knuckled fists in front of her stomach, her eyes going wide and very still. Classic trauma response.

He got up from his chair and approached her, very slowly, staying just close enough so that he could touch her arm if he felt like that would help, but far enough that she wouldn't feel cornered.

"Alyssa," he said as softly as he could. "Alyssa, look at me." She did. "We haven't been properly introduced. My name's John Watson." She didn't reply. He continued. "That's not it at all, is it? That's not why you killed him."

"No," she breathed.

"You didn't even know about the blackmail."

"I didn't know he was… I thought he could, but I didn't know he was already…. I never thought… I should've…" Her voice trailed off.

"Alyssa. You don't have to tell us why you did it." Behind him, Sherlock grunted in disagreement, but said nothing. "We do have to call the police, though."

"You're not the police?"

"We work with the police. But no."

"I don't really like the police."

"Yeah, I can understand that. In fact, I may or may not have punched a Scotland Yard superintendent in the face not long ago."

Alyssa smiled weakly at John, then looked up at Sherlock. "You're horrible," she said in a wavering voice. "But if you want to know so badly, I'll tell you."

Sherlock looked like he was about to say something but simply nodded instead.

"I killed him because he raped me. He started when I was ten years old. He did it for five years." She exhaled suddenly, as if someone had stepped on her stomach. Then she pressed the heels of her hands to her eyes. "I've never told anyone before. I've never told anyone! And I don't know even know who you two are."

"My name is Sherlock Holmes," Sherlock answered, as if that meant anything.

"That's unfortunate," Alyssa replied flatly. "Well. Now I've told you. I didn't tell anyone, all those years, because he said if I did he'd kill me, and I half believed him. And he said it would kill her, to know what we were doing" – she made a little wordless, choking sound – "to know that her best friend was… And he said he'd go to prison for a long time, and he'd make sure that she'd go to prison for an even longer time, he said he could do that, and then I'd be alone…" She took a deep breath. "And it turns out all these years he was already blackmailing her… I know I should have told her. I know that. And now I'm the one going to prison, how about that? Turns out it's me." She seemed to be talking to herself, until she looked over at John. "I never planned to," she said urgently, locking her eyes on his again. "I heard them arguing. Charles wanted James to marry me, it seemed so absurd, of course now it makes sense… With Mum dying he needed a way to leech off me. As if he hadn't… Oh God. But I didn't know, and he hasn't touched me in years, you know. It was just the way he was talking about me, like an animal or a thing… I… I reacted. I can't explain it."

"I understand," John said softly. He'd seen the way that trauma could plant landmines in a person's life like crops to be harvested far into the future, bringing forth a bounty of fear and destruction season after season, detonating randomly or regularly, but never going fallow. He knew a man, a good soldier, who calmly buried his best friend and then went home to put a bullet in his wife's head. He knew another who had tried to hold his commanding officer hostage with a hand grenade, four years after the raid that had almost taken his life. He'd never before seen a landmine actually kill the one who planted it.

John took a chance and put his hand on Alyssa's shoulder, lightly, but with that steady manner that had calmed a few soldiers teetering on the precipice of their resilience. She relaxed a little and looked up at Sherlock. "Please. Don't call them. I just need a little more time. I just need to explain to her…"

Sherlock frowned. "I solve cases," he replied. "What the police do with it is no…"

"Sherlock!" John interrupted sharply. Sherlock turned to look at him, eyebrows arched in surprise. "A word in private, please?" He squeezed Alyssa's shoulder and said with conviction, "It'll be ok. Give us a moment."