Now that Alex was back, going to our office felt like going home. The main body of the police station was made up of glass cubes that served as offices, designed so that everything could be seen by everyone: no secrets, no misconduct. No loneliness either, yet it had still felt empty over the weekend without him. I was a little ashamed that I'd missed him so much.

He shrugged his coat off with a bemused smile. "What?"

I realised that I was grinning at him. "It's just good to see you at your desk again. I need to start writing a report, so why don't you dig into Kristina's tabphone and check her Xplora messages? Then have a look at the national profiles of our people of interest."

His smile vanished. "That's a tall order."

"Better get on with it, then."

"It's early. I think you mentioned a need for coffee."

"Are you trying to worm your way out of this?" I raised an eyebrow, but I couldn't resist. "Fine, you can go and get some -- from the staff cafeteria, not Coffee Glitch. I really need you at your desk."

Alex retrieved what the coffee machine thought passed as a drink that was safe for consumption, and we knuckled down. Time crawled while I slaved over my report of the murder inquiry.

I almost jumped out of my skin when Alex said my name.

He was still rooted to his tabphone. "Kristina hadn't exchanged Xplora messages with any of the suspects recently, but I've just finished looking at everyone's national profiles. Guess what Jasper Jaydes and Mary Daniels both have in common with her?"

I crossed to his desk. "Bright Light University?"

"Yes. Jasper studied English. Mary studied robotic science. Everyone graduated in the same year as Kristina."

I frowned. "That's a big coincidence. I don't like coincidences."

"I know."

"It's a shame none of them have been very forthcoming." I grabbed my jacket. "Let's go to Kristina's flat and see if we can find something there."

***

Kristina Nixon had lived alone in a flat much cleaner and tidier than her ex-husband's. In the living room, a burgundy sofa faced a tiny glass TV, and a new armchair was snuggled next to it. Both were laden with plump Home Sweet Home cushions. Cream lamps and floral coasters stood on end tables beside them, and a pinewood dining table was squashed into the end of the room.

Alex shook the cushions on the sofa to see if anything useful fell out. I crossed to the far wall. A couple of hologram photos were projected alongside the TV, all showing a much younger Kristina. She stood with Zed Croft outside Bright Light University. She kissed Zed in a club. And...who was that?

I leaned closer to the final photo. Kristina was standing with a ginger-haired girl who was wearing a wide smile. I didn't recognise her, so I put my ilenz on, attaching the electrodes to my temples.

It scanned both faces automatically. The first national profile to pop up was Kristina's, but I shut that down and examined the profile of the other woman. Her name was Ripley Lewis. She'd attended Bright Light University ten years ago, at the same time as Kristina. I scrolled through the profile for a minute.

"Got something?" Alex was so close that his breath tickled my neck.

I swallowed hard. "Kristina's pictured with a girl called Ripley Lewis here. They attended Bright Light University together, and if this photo's anything to go by, they were good friends. Her national profile says she's Ronan's twin sister and Jasper Jaydes' cousin."

"We should try contacting her."

I turned around, pulling my ilenz off. "She's dead. According to the news reports, she committed suicide in her final year by jumping off the Music Block."

"Jesus."

"Yeah." I slipped past him. "Let's see if she's anywhere else in here."

We moved next door to the kitchen and rooted among pink tins and heart-patterned oven gloves. Nothing turned up there, but in Kristina's bedroom we found another photograph of her and Ripley. It was a real one, held in a wooden frame on her bedside table.

Alex picked it up. "Kristina must have missed her, and Zed, too. She doesn't have photos of anyone else."

"But Ripley's dead, and Zed wasn't in touch with her. So who the hell can we talk to now?" I stopped still, brightening. "Oh, I know. The staff at Bright Light University."

Alex frowned. "They probably haven't seen Kristina since she graduated."

"Whether they have or not, the university is what links everyone together. We have to go."

My sergeant sighed.

I looked at the dark circles under his eyes. "Cheer up. We can stop at Coffee Glitch along the way and get powered up again."

***

Alex spent our whole journey to Bright Light University on his tabphone, looking through ancient Xplora posts for a mention of who'd taught Kristina Nixon and Ripley Lewis. He diverted his attention long enough to order a double espresso at Coffee Glitch, and then he carried on scrolling.

I steered him down the high street as if he was blindfolded. It was nine o'clock, and the lights had finished turning on. Commuters scuttled beneath dark skyscrapers lit up with hologram hearts. Real flowers, an expensive luxury, were being hawked like tea towels by shouty young men on the metal platforms above us. Their scent mixed with the smell of rain-soaked stones from the buildings and burnt rubber from the trams.

The campus of Bright Light University was set back from the road, closed off by gates of bulletproof glass. Behind them, triangular buildings stretched a few hundred feet into the underground sky.

An eye-scanner was mounted beside the gates for the students, and two human guards in body armour were stationed nearby. We showed them our warrant cards and stated our business, and they let us inside.

The black skyscrapers made up a jungle, at least thirty of them arranged in a disorderly fashion around dark, twisting pathways that were regularly broken up by abstract statues made of glass and bright plastics, or the wackiest robots I'd ever seen, deactivated and being used as decoration. Bright Light was renowned for its robotic science course, and I suddenly wondered what they did with the rest of the bizarre projects their students made -- at least half of which were surely riddled with mistakes and didn't work. There wasn't much room for landfill down here...

We followed the winding paths, weaving around fashion gurus talking on their tabphones and serious grinders discussing their body-hacking in large groups. At every building, we paused to read the letters carved into the ground-floor windows. They were never the Music Block.

As we stopped yet again, a familiar voice piped up behind us. "Hey. Need some help?"

I whirled on my heel. "Gem!"

The Silver Star's bartender was standing with her hands on her hips. She'd recently dyed her hair lavender, and the soft colour suited her delicate features. She grinned. "Hi, Amber. Hi, Alex."

"Hi," I said. "What are you doing here?"

"I've started helping out in the Art Block on my days off." She tilted her head towards the heart of the campus. "I was just on my way to fetch a paint delivery, but I can take you somewhere if you want."

"If you're sure," I said. "I don't want to get you into trouble."

"I'll say you asked me. I can't refuse the police, can I?" She winked. "Is this about The Diamond murder?"

Alex frowned. "How do you know about that?"

"It was all over Xplora this morning. So, where do you need to go?"

"The Music Block," I said. "Alex, did you find the name of the professor?"

He glanced at his tabphone again. "Lars Stephenson."

"I have no idea who that is," Gem said cheerfully. "But I can find the Music Block. Follow me."

She led us deeper into the campus until we reached a crossroad courtyard, and she stopped outside the first skyscraper on the left. "Here we are!"

I tipped my head back and stared. I couldn't even see the top. "All of this is the Music Block?"

"Yep!"

Bloody hell. That would have been a long way for Ripley to fall.

I turned back to Gem. "Thank you."

"Any time! I hope you'll come to the pub again soon. I didn't see you with the others last night." She turned around and went back the other way.

Alex raised an eyebrow. "You didn't go out with Sebastian and Otto? I thought you'd already agreed."

"Drinks at The Silver Star is an inspector-sergeant gathering. It would have been lonely without you there." To wind him up, I added, "I've just spent my free time wandering the city in the dark instead. Sometimes the rain."

He frowned, and I grinned.

The ground floor of the Music Block was a triangular lobby surrounded by lifts and stairwells. Students hurried up the steps or emerged from lift cars. A circular desk stood in the centre of the room, manned by a robot. I looked at Alex when we reached it.

One corner of his mouth quirked upwards. "Where is Professor Stephenson?"

"Room 34, on the fifth floor," the robot said.

We looked around us. Electric signs hung over every staircase and lift. Alex started towards the stairs that would take us directly to the fifth floor.

"No," I moaned. "I can't keep up with you. We're getting the bloody lift."

***

When we reached the fifth floor, I was thankful to find that the doors had name plaques. The one labelled Professor Stephenson was wide open, and its occupant was sitting at his desk. He was a lean, middle-aged man who looked up over the rims of his wireless glasses as we approached the doorway, offering us an automatic smile.

I stopped with my toes over the threshold. "Professor Stephenson?"

"That's me," he said. "Do come in."

We entered properly and flashed our warrant cards.

"Inspector Rames and Sergeant Sullivan," I said. "Socrico Police. We're here to ask some questions about Ripley Lewis. She died here in 2176. We believe you taught her."

Professor Stephenson furrowed his brow. "Yes. She jumped off this building in her final year. It was very tragic -- and a long time ago."

"It's cropped up in a recent murder inquiry. Her best friend was killed this morning. Kristina Nixon."

Stephenson sat back. "I just read about that on Xplora. But I didn't know Kristina."

"Then tell us about Ripley," Alex said.

"It was a shock." Stephenson gazed across the room, his eyes turning distant. "It still is. Apparently she'd been depressed, but we never knew because she wasn't diagnosed. The police found a diary afterwards, filled with suicidal thoughts and methods on...well, you know. How to do it."

Bloody hell. That was as chilling as it was tragic. "Did she never seem unhappy in your lectures?"

His mouth turned down as he thought. "I suppose she was a little stressed from time to time, but all my students are. It was her final year. She had a lot of things to get done in order to take home the degree she'd slaved over. That's why it was such a shock."

"You mentioned that you didn't know Kristina," Alex said. "Did you never even see her? Did she ever wait outside the classroom for Ripley?"

"No, but that boy sometimes did." Professor Stephenson ran a hand through his thinning hair. "Er...Zed somebody?"

"Zed Croft? Kristina's boyfriend at the time?"

"That's the one." The professor sat back. "I believe they were all good friends."

***

"I wonder who else was friends with those three," I said as we walked across campus. "Ripley's relatives, Ronan and Jasper? Whatever the case, their links here are strong. Kristina was best friends with Ripley, married Ripley's brother, and worked for Ripley's cousin. She dated Zed while they were here, and she and Zed took robotic science with Mary Daniels."

Alex frowned, scanning our surroundings. He stopped beside another dark building. "This is the Robotic Science Block."

We discovered that Kristina's old professor, Minerva West, was teaching on the sixth floor. As we rode the lift up there, Alex pushed his hands into his coat pockets and glared at the opposite wall.

"What?" I asked.

He glanced at me. "I was just wondering who'd have Ripley's diary now. Us? Or do you think it was given to her parents afterwards?"

"You want to look at it?"

"She might have mentioned Kristina."

The lift doors slid open, and we stepped out. I hummed thoughtfully. "Maybe. I'll see what I can do when we get back to the station."

Professor West's room was a workshop filled to the brim with exactly what I hated most -- electronics. Wires were gathered on the ceiling and hanging low over the students' heads. Robots were sprawled across work surfaces, their chests or backs open. Tablets hovered in the air and cluttered up desks. A crowd of students flocked around it all, constantly moving.

Minerva West, an elderly woman wearing dungarees, was standing next to an eight-foot robot at the front of the room and talking to one of her charges. He had his back to us, so all I could see of him was his tall frame, blond hair, and strange jacket. BITCH was sewn across the denim.

"I don't know what else to say, Evan," Professor West murmured. "If you keep on handing them in late, you just won't get your -- " She caught sight of us. "Oh."

The boy took his chance to escape into the crowd.

Professor West strode across the room to us. I went through our introductions and asked if we could speak with her about some former students. She came out and shut the door behind her with a liver-spotted hand.

"Kristina Nixon was an old student of mine," she said immediately. "Is that who you wanted to talk about? I saw an article on Xplora by that big journalist, Clyde Edwards, saying she was murdered."

I gritted my teeth. Bloody Clyde.

"Can you tell us anything about her?" Alex asked.

"Oh, she was very passionate about this subject. She was desperate to work for a company like Ackerman Electronics or Castle Robotics, but she didn't have the same spark that some of my other students did."

"Like Zed Croft or Mary Daniels?"

West shook her head vehemently. "No, not Zed! He was too lazy. I have no idea if he was talented or not -- he never turned in a scrap of work. Mary, though, was my star pupil. She hardly had anything to learn in the beginning, yet her talent somehow grew even greater. She could have hacked a bank without leaving a trace."

"Right..." That was something to consider. "Going back to Kristina -- she and Zed were in a relationship, weren't they?"

"Yes. Lord knows what Kristina saw in him when she was so passionate and he was so lazy. They broke up near the end of their final year. I think it was because of Ripley, you know. Witnessing that sort of tragedy must have torn the relationship apart."

"Ripley Lewis?" Alex repeated. "They witnessed her suicide?"

"Yes!" Professor West's eyes brightened. "I'm surprised you didn't know. There were all sorts of rumours flying around afterwards! It was just Kristina, Zed, and Ripley -- no one knows where the others were. The story goes that the three of them got roaring drunk and went up to the top of the music tower. It was Ripley's idea. She told them how much she hated her life and just jumped right off. But people whispered -- "

I frowned. "Hang on, you said 'others.' Were they all friends? Kristina Nixon, Zed Croft, Ripley and Ronan Lewis, and Jasper Jaydes?"

"Yes. Thick as thieves, the five of them were, or so they say. Not so thick afterwards."

"What about Mary?"

"My Mary Daniels? Never." Her speech quickened with excitement. "Anyway, people said afterwards that it was really Kristina's idea to go up to the roof. It was common knowledge that Zed had been unfaithful to her during their time here, and lots of people thought he was sweet on Ripley. You know what students are like. Young and wild, changing their relationships at the drop of a hat. And you just have to wonder whether it was true, and Kristina decided she'd had enough."

***

Our final destination was back where we'd started -- the Music Block. The roof was easy enough to get to. There was no locked door to keep students away from the danger, or even a chain across the steps to warn them off. We strolled across a wide sheet of thick, slippery glass and stopped a little way from the edge. The people below us looked like ants.

I tried to imagine Kristina, Zed, and Ripley standing up here. I tried to imagine Kristina pushing Ripley. I tried to imagine Ripley jumping off.

"It's so easy," I said. "Easy for someone to have pushed her; easy for her to have jumped. But rumours are rumours. Evidence confirms it was a suicide. No one can argue that she wasn't planning to kill herself."

Alex stared across the sky at the other glassy rooftops. "I want the diary. I still think it would help us."

"Okay, fine. But before we try looking for it, I want another word with Kristina's boss and her old boyfriend. We'll see if we can get them to talk about their university days." I turned away from the edge.

"Right. One more thing..." Alex's voice lightened. "Where did you go to university?"

"I didn't. I joined the police through an apprenticeship." I threw a grin over my shoulder as I descended the stairs. "Why, did you think I was a wild student, Alex?"