She dreamed about the river.
Not the Thames specifically — just water, wide and brown and moving with that same indifferent authority, carrying things she couldn't see below the surface. She woke at five-thirteen and lay still for a moment, listening to the flat. Her mother's breathing through the wall. Kofi shifting in his sleep. The distant sound of a bus taking the corner on the main road.
She got up.
By six she was at the kitchen table with her laptop, a mug of tea going cold beside her, and three browser tabs open.
The first was the tide table she'd found the night before. The second was a forum thread she'd located after midnight — a community of Thames mudlarkers, people who walked the foreshore at low tide searching for objects the river had given back. They posted finds: clay pipes, Roman coins, Victorian bottle glass, the occasional piece of something more recent that the current had decided to return. The thread was eighteen months old but the forum was active. Someone had posted three days ago about conditions near Woolwich Reach.
The third tab was Ethan Mears's development blog. She had it open to the Getting the Ballistics Right post.
She read it again. Slowly this time.
He had cited three specific sources in the post — two online ballistics forums and a YouTube channel run by a former military instructor who reviewed firearms for civilian enthusiasts. She clicked through to each one. The forums required registration. She registered. She spent forty minutes reading thread histories under the username EMears_Dev, which he had apparently not thought to make anonymous.
He had been active for fourteen months.
He had asked questions about suppressor mechanics. About the difference between subsonic and standard ammunition in terms of audible report. About what a nine-millimetre round sounded like in an enclosed residential space.
She wrote it all down.
She was at the office by eight-thirty. Mr. Adeyemi was already in again, same loosened tie, same expression of a man who had made peace with the hours a long time ago. He looked up when she came in.
"How are you doing?" he asked. Not perfunctorily. He meant it.
"Working," she said.
He nodded. That seemed to satisfy him.
She sat down, opened the Southwark file, reviewed it properly this time, finished her revision note by ten, and sent it to the associate responsible. Then she opened her personal notes document and stared at the screen.
The self-defence claim was the thing she kept returning to.
It was clever. She had to give it that. In a case with no weapon, no clear motive established yet, and a security camera gap that could be argued as coincidental, a self-defence narrative shifted the entire weight of the investigation. It turned Ethan from perpetrator into victim. It gave him a reason for the struggle, a reason for Lena to have been holding something, a reason for chaos and accident and tragedy rather than planning and execution.
The problem — and she turned this over carefully, the way she had learned to turn over contract clauses looking for the thing that didn't sit right — was that self-defence required a weapon.
And the weapon had to have come from somewhere.
A firearm didn't materialise. It had a manufacture date, a serial number, a point of sale, a chain of custody. If Lena had brought a weapon to that apartment, someone had sold it to her, or given it to her, or she had inherited it, or she had obtained it illegally. Any of those pathways left a trace. People were the traces — sellers, middlemen, friends who knew, moments that were witnessed.
Lena Obi had been a twenty-two-year-old communications student with no criminal record and, as far as Zara had ever observed, no interest in anything that could not be bought at a market stall or streamed on a laptop.
The idea that she had walked into that apartment armed was not impossible.
It was simply not Lena.
Which meant if the weapon existed, it hadn't been hers.
Which meant Ethan had introduced it to the scene himself — had brought it in, had used it, and had removed it before the corridor camera came back online. The self-defence story was not a defence. It was a retroactive construction. A frame built after the picture was already taken.
She needed to prove where the weapon had come from.
At noon she took her lunch break and walked to the nearest library. It took her twelve minutes. She used one of the public computers and pulled up the forum thread she'd found that morning — she didn't want this search tied to the firm's network, even tangentially.
She found the mudlarker who had posted near Woolwich Reach. His username was foreshore_frank. His post history showed he went out three or four times a week, mostly early morning, mostly east of the Barrier. He had a photo attached to his most recent post — a long stretch of dark foreshore at low tide, the Thamesmead towers visible in the distance.
She sent him a message through the forum's private system.
She kept it simple. She said she was a researcher looking into objects that might have entered the river in the Greenwich area during the early hours of the ninth. She said she was specifically interested in anything metallic, non-organic, recovered in the Woolwich Reach corridor or east of it. She said if he had found anything or knew someone who had, she would very much appreciate a conversation.
She did not mention the police. She did not mention Lena. She gave her personal email address and her first name only.
Then she walked back to the office and ate her sandwich at her desk.
The reply came at half past three.
"Haven't found anything myself but I was out on the morning of the 10th — tide was right — and a woman I know, goes by Pats, she found something near the Woolwich steps that she wasn't sure what to do with. Bit unusual for a find. She reported it to the foreshore officer. Don't know what happened after that. Can try to put you in touch if useful."
Zara read the message twice.
A bit unusual for a find.
She wrote back immediately. Yes. Please do. Thank you.
She picked up her phone and called Detective Ola.
He answered on the second ring.
"Has anything been recovered from the Thames near Woolwich Reach?" she said. "In the last forty-eight hours."
A pause. Longer than usual.
"Where did you get that from?" he said.
"Tide tables and a mudlarking forum," she said. "Has something been recovered or not?"
Another pause.
"I'm going to need you to come in," he said.
The station was in Lewisham. It smelled like every municipal building she had ever been in — floor cleaner and recycled air and something institutional underneath that had nothing to do with cleanliness. Ola met her at the front desk and walked her through a corridor to a room with a table and two chairs and a window that looked onto a wall.
He sat down. She sat across from him.
He put a photograph on the table between them.
It was evidence photography — a still taken against a white forensic background. A compact pistol, water-damaged, its finish mottled with river sediment. It was small. Purpose-built for concealment rather than accuracy at distance.
"Recovered from the foreshore at Woolwich this morning," he said. "A member of the public found it on the ninth — early hours — and reported it to the Thames foreshore authority. It was logged and then flagged to us this afternoon when the connection was made."
Zara looked at the photograph. At the compact frame. At the shape of it.
"Ballistics?" she said.
"Preliminary match to the round recovered from the scene," he said. "Nine millimetre. We're waiting on full confirmation."
She nodded slowly.
"Serial number?"
He held her gaze for a moment.
"Filed down," he said. "Professionally. Not a casual attempt."
That was the thing that landed differently. Not a panicked scratch with a kitchen knife. A deliberate, pre-meditated removal. Which meant the weapon had been prepared before it was used. Which meant this had been planned before Lena walked through that door.
"He bought it illegally," Zara said. "Or had someone buy it for him. The serial number removal is the link — find who does that kind of work and you're inside the supply chain."
"We're aware," Ola said. "Ms. Ademi—"
"There's something else," she said.
He waited.
"His forum account. EMears_Dev. He's been active on a ballistics community for fourteen months. Asking specific questions — subsonic ammunition, suppressor mechanics, audible report in enclosed spaces. He was researching how to do this quietly before he ever pulled a trigger."
She slid her phone across the table. She had screenshotted the relevant posts that morning before she came in.
Ola looked at them. He was still for a moment.
"How did you find this?"
"He cited his sources in his development blog," she said. "The sources led to the forums. The forum account wasn't anonymised."
"He didn't think anyone would look."
"He thought the camera gap would be enough," she said. "He thought the self-defence story would cover the rest. He forgot that the internet keeps records of the things you ask before you need to ask them."
Ola looked at the screenshots for another long moment. Then he picked up his phone and made a call. Short, quiet, specific. When he ended it he set the phone down and looked at her.
"The forum records can be subpoenaed," he said. "If his account activity predates the relationship with Lena by enough margin—"
"Fourteen months," she said. "They were together for eight."
He understood what that meant. The research had begun six months before Lena Obi entered his life. Whatever had driven Ethan Mears toward this was not about Lena specifically, not in its origin. She had become the object of it. But the preparation had started before she existed to him.
That changed the character of the case entirely.
"This goes to the CPS," Ola said, almost to himself.
"It should," Zara said. "But the weapon is the cornerstone. Everything else is scaffolding. You need the ballistics confirmed, the supply chain traced, and the drone recovered if possible."
"The drone."
"He used it to carry the weapon to the river. If the drone was recovered — or if the launch can be established through the building's rooftop access logs — you've closed the transportation question. The self-defence claim only stands if the weapon was Lena's. Prove it was his and the whole structure falls."
Ola looked at her for a long moment.
"You're twenty-two years old," he said.
"Twenty-three in March," she said. "And I've read a lot of case files."
He almost smiled. Not quite.
"I'll look at the rooftop access logs," he said.
She stood. Picked up her phone. Straightened her coat.
"Let me know what you find," she said. "Formally or otherwise."
She walked back through the corridor and out into the grey afternoon.
She was on the bus home when the message came from foreshore_frank.
"Pats says she's happy to talk. She kept a photo of what she found before she handed it in. Says it looked like someone had tried to strip it. She didn't know what it was at first — thought it was scrap. Then she looked closer."
Zara typed back: Can she send the photo?
Three minutes later, her phone buzzed.
The image was low resolution, taken on a foreshore at dawn. Dark riverbank, pale sky, the object lying in a small depression of wet silt. It was unmistakeable. Same compact frame. Same mottled finish.
The same gun.
She saved the image. Added it to her notes document. Wrote the time and date.
Then she looked out the bus window at the city going by — the shopfronts and the tower blocks and the people moving along pavements with their collars up against the cold — and thought about the thirty-nine-minute window that had started all of this.
He had planned every second of it. The camera. The drone. The filing of the serial number. The self-defence story, prepared and ready, his solicitor presumably briefed before the body was even cold.
But he had not planned for a woman who wasn't at the party.
Who was home reviewing a lease dispute.
Who read tide tables and mudlarking forums the same way she read contracts — looking for the clause that didn't fit, the line that sat differently from everything around it.
She added one final note to the document.
The water gave it back.