We took Ronan down to the police station while a couple of PRBs made a more thorough examination of his flat. Just ten minutes after we'd settled Ronan in an interview room, Dixon received a report from the robots to say that they'd found a little more evidence and were bringing it down to us.

"After you've interviewed Ronan," Dixon said to me, "I want you to go home. You've had a shock, and it's going to catch up with you."

I straightened my back. "But, sir -- "

"No more arguing. I've let you do what you like today, but now that we have the murderer in custody, you'll follow my orders again. Alex can take you home."

I twisted my fingers together in my lap. "Yes, sir."

"Talk to Cassia. See if she can leave the mortuary early and keep an eye on you."

"I don't need keeping an eye on, sir."

"Do you want to be taken off this investigation?"

"No!"

"Then I suggest you do as I say." His gaze moved over my shoulder before I could argue again. "Yes?"

I twisted around in my seat. Laney was standing in the doorway. "Ronan Lewis' solicitor is here, sir."

"Thank you," Dixon said. "Tell them my officers will be another few minutes."

***

"This interview is being video-recorded and may be given in evidence if your case is brought to trial. We are in an interview room at Socrico Police Station on 13th February 2186. The time is 16:00. I am Detective Inspector Amber Rames. The other police officer present is Detective Sergeant Alex Sullivan. Please state your full name and date of birth."

"Ronan Lewis. 2nd July 2155."

"Also present is Ronan's solicitor. Ronan, I will remind you that you do not have to say anything, but it may harm your defence if you do not mention something which you later rely on in court. Anything you do say may be given in evidence."

I laid a hand-written receipt for cyanide on the table, found by the PRBs at the bottom of the sugar jar. Alex added the duelling pistol we'd discovered in the kitchen and the one we'd taken off Ronan's person, plus a paper printout displaying several shots of Evan's ski-masked killer pushing him in front of the train. Ronan's solicitor leaned forward and inspected the evidence, even though we'd been obliged to explain it to him beforehand.

I tapped the receipt. "We found cyanide in your kitchen, Ronan."

He shook his head. "Okay, I shouldn't have that. But no one's been killed with cyanide. I don't get -- "

My temper flared. "I was almost killed with cyanide this morning. You gave it to Evan Archer with the instruction to put it in whatever drink I ordered at Coffee Glitch. You wanted me off the scene to shake up the investigation. This receipt confirms that it was you who made the illegal transaction for potassium cyanide yesterday afternoon. You were panicking as we started to close in."

Ronan sat back, his eyes wide. "I don't know what you're talking about."

"We spoke to you about Duty Bank yesterday. Is that what you killed Kristina and Zed for?"

"I would never kill Kristina!" Ronan's voice rose. "Never! I was angry, but I never stopped loving her! Now that she's gone, I wanted some photos of her around the flat. Real photos I could treasure. I thought it would be cheaper if I printed them myself. I bought the cyanide to act as a fixer to stabilise the images. You have to believe me."

I remembered the photo paper Alex had found at his flat. But I shook my head. "Cyanide is an unusual option for a fixer. And I thought you were a struggling architect. Photo paper is very expensive."

He looked away. "I bought that illegally, too."

"When did you buy it?"

"At the same time as the cyanide," he muttered feebly.

"Very convenient." I tapped the CCTV images. "So, is that you in the ski mask? Did you push Evan Archer?"

"No! I don't even know who he is!"

"Fine. Let's move on to our last piece of evidence. Why do you own two duelling pistols? You know that's illegal."

"I think it's bullshit. A man should be allowed to protect himself. You've seen the dump I live in. It's not safe there."

"And that's all?"

"Yes." He turned his face away. "I refuse to answer any more stupid questions."

***

Alex walked me home after the interview. Frustration made my blood run hot and my limbs restless, and I did a better job of keeping up with his natural pace than usual.

I wanted evidence to charge Ronan with the murders of Kristina and Zed, and I wanted it now -- because now, more than anything, I wanted the investigation to be over. I'd watched Zed Croft die despite my best efforts, I'd almost been poisoned, and I'd witnessed Evan Archer being hit by a train. The energy I felt was a strange, weary one: a last surge of determination before I burned out altogether.

When we reached my front door, I looked up at Alex. "Do you want to come in for a few minutes before you go back to the station?"

His mouth curved into a gorgeous smile. "I'd like that."

The door scanned my face and opened. I led him in and kicked it shut behind us, my gaze never moving from his mouth.

I must have stepped towards him, or him towards me, because suddenly we were kissing. His arms curved around my waist, and I was glad of his support because it felt like the world had fallen away beneath me. I was finally somewhere else; something else. Just need.

My hands found his tie and tugged it. He stepped back with an air of reluctance, shackling my fingers. "Amber, no. I'll never get back to the station if you do that, and Dixon would ask where I'd been."

I lowered my hands and turned my face away. "And we don't want to be arrested. I think."

Squeezing past him, I retreated into the kitchen. Arriving to find the room empty suddenly reminded me that the day wasn't over. "Oh, no! Mitzy! I'll have to go and get her."

"Ah." Alex followed me and leaned against the counter. "I think Cassia must have called your mother earlier. Then your mother called me and said Mitzy's blood tests came back negative, so she's releasing her from the surgery and taking her home for the night."

I stared at him, dumbfounded. "Mom called you?"

"She said calling you was pointless because you'd argue with her about it. You don't need an injured cat on your hands after the day you've had, so she'll be bringing Mitzy back to you tomorrow instead."

"That's not fair on her -- "

"I got the impression that she loves your cat and she's excited to have her." Alex raised an eyebrow. "So you can forget going over there and trying to argue about it in person, too."

I dragged a hand through my hair. "Okay, fine."

But now that I had no cat and no work, shock was setting in again. I wondered how long it was going to be before I ever got a good night's sleep. I knew that when I closed my eyes tonight, the train would be there.

"I'm sorry about today," Alex said softly. He pulled me against his chest. "I'm sorry about everything."

"It's okay." I laid my head down, strangely at peace in his arms even though his touch still electrified me. "It's better when I'm with you."

"But now I have to go."

"So I'll ring Gem. We'll have a girl's night in."

"All right." Alex sighed deeply. "Tomorrow night, we're going to spend time together without any murders intruding. Come to my place for Valentine's dinner."

My spirits lifted a little, and I raised my head. "That sounds great. I love your flat -- and I'm especially fond of your bedroom."

His lips quirked. "Funnily enough, I feel the same way when you're in it."

***

"What the hell is this?" Cassia's voice was laced with disapproval as she shrugged her coat off in my living room an hour later.

"A major incident room." I stopped in the middle and spun to face her and Gem. "My major incident room."

I'd found a marker pen (not permanent) and written notes all over the far wall. The coffee table was covered in old scraps of paper I'd reused to represent the evidence, with things like potassium cyanide and duelling pistols written on them. I'd also gone to the costly pains of printing out the front pages of some national profiles, alongside the CCTV images of the train station Alex had shown Ronan earlier, more CCTV images from the murder of Kristina and Zed, and Ripley's tablet.

Balanced on and around these things were the only acknowledgements that I had guests: three cups of tea and a large slab of chocolate.

"Amber," Cassia said slowly. "I thought we were having a girl's night in. You need a break. This -- "

" -- is my job," I cut in. "I have to bring the murderer to justice."

"But, Ambie -- "

Gem surveyed the room with a cheeky glint in her eyes. Her hair was bright red today and plaited neatly. "This looks like fun, and you know we'll never be able to persuade her to rest until she's finished it."

"And you enjoy helping me." I picked up two more pens from the coffee table and threw them at my sister and my friend. "You secretly love playing detective, Cassia."

She caught her pen with one eyebrow raised. Gem's flew into the hallway.

"Okay," I said when she'd retrieved it. "Let me talk you through the investigation from start to finish. One rule -- this is sensitive information. What I tell you in this room stays in this room."

"Right!" Gem slammed the door shut for emphasis.

I turned to the far wall and pointed at a timeline I'd drawn. "We'll start with the bare bones of the investigation. Just after 05:00 on the eleventh of February, Kristina Nixon was clubbed to death with a set of antique weighing scales at The Diamond Hotel. This was done by a hacked hotel robot named Alpha. No trace of the hacker's online identity was discovered.

"On the same day, Zed Croft was shot at Duty Bank by his own robot. He died shortly afterwards. Mary Daniels was a witness to the incident and claims the robot told Zed he had been a very bad boy -- just as Kristina had been told, that morning, that she had been a very bad girl. We located the robot a while later, but again, there was no trace of the hacker.

"No murders on 12th February, but the gun that was used to kill Zed Croft was found in his old dorm room at Bright Light University. Evan Archer, a current student, must have planted it there. If we skip forward to 13th February -- today -- I can explain who he is. This morning, Evan attempted to murder me by spiking the drinks I ordered at Coffee Glitch with potassium cyanide. He then fled and eventually entered Socrico Train Station, where he was pushed in front of an oncoming train by a man in a ski mask.

"Later in the day, we searched the flat of Ronan Lewis. We discovered potassium cyanide there, purchased illegally. He was arrested on suspicion of attempted murder and is currently being detained in the custody suite." I let my hands fall to my sides. "Any questions so far?"

Cassia was frowning at a CCTV shot of The Diamond Hotel. "If you've charged someone, what are we doing this for?"

"We only have physical evidence linking Ronan to my cyanide incident. There's nothing solid yet that will prove he murdered Evan in court, and nothing connecting him to the murders of Kristina and Zed at all. So I want to think like he thinks and understand where to find the evidence."

Gem picked up a mug of tea. A scrap of paper was stuck to the bottom, and she pulled it off. "Coffee poisoned with potassium cyanide x2. What's this?"

"Our pretend evidence," I said. "I couldn't bring it all home with me."

"But she would have if it had been possible." Cassia shook her head with a wry smile. "Have you even eaten yet, Ambie?"

"Eating properly comes later, but you can help yourself to some chocolate." I walked to the opposite side of the coffee table. "Let's tack the evidence on the wall. First: the CCTV images of Kristina's murder, the weighing scales, and Alpha the robot all need to be put on the timeline at 05:00, 11th February. Zed's evidence is the bank robot, the rifle used to shoot him, and the CCTV images from the shooting. The attempted poisoning needs the coffee sticking up next to it, and the murder of Evan needs the train station's CCTV images and the cyanide coffee scraps to remind us of the link. Then put the cyanide paper with the arrest of Ronan and add duelling pistols."

Cassia and Gem stuck the paper evidence on the timeline for me, and then we had a minute's pause while we surveyed our work. I sipped my tea and ate a chunk of chocolate.

"Now," I said, "let's have Ronan Lewis' national profile."

"But there are loads of people here," Cassia said. "Don't you want them, too?"

"No. Just Ronan."

She handed me Ronan's profile, and I stuck it above the timeline.

"What's his motive?" Gem asked.

"A long story. In 2173, he began studying at Bright Light University. He shared a student flat with Zed Croft. They met with his sister, Ripley Lewis; his cousin, Jasper Jaydes; and his future wife and Zed's classmate, Kristina Nixon. The infamous five were formed."

Gem pointed at a different national profile. "Where does Mary Daniels fit in?"

"She was a classmate of Kristina and Zed, and she was bullied by them." I swallowed. "Kristina and Zed entered a relationship. But near the end of their final year, Ripley committed suicide by jumping from the roof of the Music Block, and they witnessed it. You can find her tablet on the table, documenting the suicidal thoughts that led up to the moment when this friendship group became potential enemies.

"Kristina broke up with Zed and married Ronan. Five years later, Ronan divorced Kristina after she sold plans for a bank they'd dreamed up together to Zed: Duty Bank. But, left with less money than she'd expected, Kristina was forced to work as a receptionist for Jasper at The Diamond Hotel. Meanwhile, Mary Daniels had been struggling to hold down a job because she was psychologically scarred by her torment at university. Working for Zed, her bully, appeared to become her only option."

Gem frowned. "I wouldn't do that even if I was desperate."

"What about Clyde?" Cassia asked.

"He's a dead end. Can you pass me Evan Archer's profile? He's the hacker."

She did, and I tacked it up next to Ronan's.

"While Evan might have failed to kill me," I said, "he excelled at hacking the robots. He studied robotic science at Bright Light, and according to Professor West, he'd hacked robots without leaving a trace before. Seems conclusive that he's our hacker here." I stepped back and picked up my cup of tea. "Okay, I've laid it all out for you now. Time to think about where we might find more evidence."

"What about the train station?" Gem asked. "Ronan could have dumped the ski mask in a bin there."

"The PRBs have searched every inch of it."

Cassia came alongside me and studied my notes. "What's all this about him being at a building site? Have you looked there?"

I perked up. "No. I'll call Alex."

I placed an audio call to him so that he wouldn't be able to see what I was doing. He answered on the first ring. "Amber, are you all right?"

"Yeah. I don't suppose you're still at the station?"

"I am. We sent some PRBs to search Evan's dorm at Bright Light, and I was just waiting for them to get back. They didn't find anything to help us."

"Have you checked the building site Ronan's been spending so much time at?"

"Yes. There's nothing there, either. Evan's bank account also hasn't turned up any results: whoever contracted him hadn't paid yet. I'm calling it a day." His voice softened. "Why are you asking? I thought you were taking a having a girls' night in with Cassia and Gem."

"I am," I said quickly. "It just popped into my head. That's all. Goodbye."

***

Cassia, Gem, and I gorged on pizza and watched some films, but I couldn't stop thinking about the investigation. After they'd gone home, I called my old sergeant, Nina Howell, in the hope that she could cast a fresh eye over the facts. But she'd been keeping up with the news on Xplora -- and my governor.

"No, I'm not helping you." Nina looked vibrant on my tabphone screen, cosied up in a plum jumper with dark hair hanging over her shoulders in two French braids. But she was without her usual dimpled smile. "You're supposed to be resting. Dixon called me to make sure you didn't call me to talk about work."

I tucked my legs underneath me with a sigh, disappointed that I'd been betrayed. "But what am I supposed to do?"

"Go to bed early. Or read. Or eat chocolate."

"I always eat chocolate." I raised the plate of leftover chocolate so that she could see. "And I don't want to go to bed. I want to talk with you."

"Then let's talk about something else."

"Okay." I racked my brain, but I couldn't think of anything else to talk about. Eventually, I realised it was very quiet on Nina's end of the line. If her girlfriend was in the flat, she wasn't making any noise. "How's Erin?"

"Good. She's in New London with a client, but she's due back tomorrow."

"Great. How's Rosek?"

"Still good. I still miss you, but I feel settled now."

"Is your sergeant still pulling his weight?"

Nina shrugged. "Yes, but we'll never be friends."

"You should come back and visit the rest of us, then. See my ugly mug in real life."

Finally, she released her wide smile. "I think I'll have to wait a while. I don't expect the chief super would be pleased if I asked for a holiday so soon. However, I'd love to meet the man who's taken my place. I remember him being tall, dark, and handsome when I saw him on video during the Ackerman inquiry."

I blushed. "Um, yes, he is. How are your investigations? Got anything interesting?"

"Come on, let's have a conversation that isn't about work. How's Mitzy?"

"Mom's got her. She had to stay overnight at the clinic yesterday."

Nina's eyes widened. "What happened?"

I explained about Mitzy going missing up to the point where Alex had carried her to the clinic with me.

"Alex?" Nina repeated. "What was Alex doing with you?"

"Walking me home. He gets as worried as Dixon about Clyde hanging around."

"Oh, how sweet! Or maybe even romantic...?" She grinned.

"Nina!" I felt my face turn hot again.

"I know, I know, I shouldn't joke about a police officer indulging in an illegal activity like that. But if I were you, I would be very tempted." She winked. "Especially when it's Valentine's Day tomorrow."