Ella burst into the office and found Luca and Ross already waiting for her. She threw down her things on the table and replayed everything in vivid detail. Her head buzzed with the kind of clarity that usually only came with a fifth of whiskey or a well-timed epiphany.

Ross leaned over the desk. ‘Ella, talk to us.’

She caught her breath and launched into a spiel she’d been unconsciously practicing as she sped here. ‘Amelia Blackwood. Felix’s sister. She’s our unsub.’

How had she missed it? All this time, the killer had been right there, sitting pretty in the fifth row while Ella spilled her guts on stage.

‘His sister? I didn’t know he had one.’

'She's right,' Luca said. 'At the cult's meeting, I saw a figure with flaky skin on her face.'

Ella nodded furiously. ‘Yeah. She was at my lecture at NYU a few days ago, which means she must be a student there, meaning she knows Marcus Thornton. She had a scar on her cheek but had tried to cover it with makeup. Same with her skin condition. There was a tattoo on her wrist too – some triangle-circle hybrid thing.’

‘One of the five from our crime scene. The person I saw at the meeting had tattoos on their wrist too.’

‘Felix confirmed there were only two women in the Order. His sister was one of them.’

Ross rubbed his chin. ‘Alright, so we've got a name. What about motive?’

‘That book Luca found? The author was disfigured. Used alchemy to transform herself into something perfect. Amelia's following the same playbook.’

‘But why kill people?’

‘We’ll ask her that when she’s in cuffs,’ Ella said. ‘And remember those threatening notes someone was leaving on Felix’s desk? Well, Amelia lives on the farm with him. She could easily have slipped them there. Either to frame Ezra or her brother for the murders.’

‘The poison angle fits too.’ Luca paced the length of the evidence wall. ‘A woman working alone couldn't overpower victims physically. But she could get close to them, gain their trust. ’

Ross said, ‘And Felix never mentioned that his sister was part of the group?’

'No. He secretly wanted us to dismantle the cult and free his sister from their grip. Apparently, she was consumed by the thing.'

‘Figures,’ Ross said. ‘But if you couldn’t find this Amelia woman at the farm, then where the hell is she?’

‘Let me introduce Exhibit A.’ Ella scooped up the book she’d stolen from Felix’s bedroom. ‘This is Beyond the Veil by Lydia Soulwright.’

Ross scrubbed his face. ‘Oh God. Not this clown.’

‘You know her?’

‘Yeah. Sadly I do.’

'Well, Hawkins here has rubbed shoulders with her because she's a member of the Order.' Ella flipped through and showed Ross and Luca the signed inscription. 'Felix confirmed it too. That's why he's got a personal message from her.'

‘I saw that book at the Order’s meeting too.’

Ross took the book and said, ‘My wife loves this woman. She’s going to see one of her shows tonight.’

Ella’s ears pricked up. ‘Shows? Tonight?’

‘I think that’s what she said. Some theater downtown.’

Luca was already at his laptop. He hammered the keyboard then said, ‘Lydia Soulwright, a.k.a. Margaret Walden. Born 1970 in Peoria, Illinois. Says here she's doing a live show at Gramercy, plus a book signing after.’

‘Right. And what about her? What’s she got to do with this?’

‘Because she’s the final element. We’ve had earth, water, air and fire. The only one missing is spirit, or aether, whatever you wanna call it.’

‘Quinta essentia,’ Luca said.

Ella snapped her fingers. She hadn’t even made that connection herself. ‘Perfect, Hawkins. How long until Lydia’s show starts?’

Luca checked his watch. ‘Fifteen minutes. Starts at six PM.’

A familiar electricity surged through Ella's blood as she yanked her Glock free. This must have been the same comfort a surgeon must feel gripping a scalpel or a violinist cradling their bow. She dropped the mag, counted fifteen brass soldiers standing at attention, then slapped it home. One in the chamber made sixteen chances to end this case painlessly.

‘We go in hot. Make sure Lydia is safe, then devour the place in search of Amelia. How does that sound?’

‘Crystal,’ said Ross.

‘Ditto,’ Luca said .

She thought of the victims. Marcus Thornton, buried alive by his life's work. Sarah Chen drowned in the waters she'd devoted herself to understanding. Tessa Windham, falling from the sky she'd called home. Victor Ashford, consumed by the fires of his art.

And now Lydia Soulwright, prophet of spirit, about to be martyred for the cause.

Not on her watch. Not while there was breath in her body and a bullet in her gun.

The Alchemist had transmuted her last. It was time to introduce her to the one element she couldn't control.

The fury of a woman on a mission.