The interrogation room had transformed into an impromptu dressing room. Ella circled Luca like a sculptor inspecting her work, comparing him to Felix Blackwood, who sat slumped in his usual chair.

The black hair dye had taken well enough. There was no hint of Luca's natural brown showing through. Amazing what you could accomplish with a box of Midnight Noir and the sink in the precinct bathroom. The airsoft mask covered most of his face, leaving just his eyes visible. Between that and Felix's oversized hoodie, he looked exactly like the kind of person who'd join an underground alchemical cult. Side by side, Luca and Felix could have been brothers.

‘Turn around,’ Ella said.

Luca rotated, the number 9 on his back catching the fluorescent light. The fabric paint had cracked in places, giving it that properly worn look that couldn't be faked.

‘Now walk.’

He took a few steps and mimicked Felix's slight slouch. They'd spent twenty minutes studying Felix's movements - the way he led with his right shoulder, how his feet turned slightly inward when he walked.

‘The stance is wrong,’ Felix said from his chair. ‘I don't walk like I'm about to arrest someone.’

‘Less cop, more farm boy,’ Ella agreed. ‘Try again.’

Luca adjusted his posture and softened his usually-rigid bearing into something more casual. ‘How’s that? This isn’t how farm boys walk, by the way. I was one.’

‘Better.’ Ella nodded. ‘Now let's hear the accent.’

Luca cleared his throat. When he spoke, his usual Boston inflections had vanished, replaced by pure New York attitude. ‘Yo, how's this?’

Felix winced. ‘Maybe dial it back like twenty percent. You sound like a cab driver.’

‘He’s right,’ Ella said.

‘How you doin’? This mask is itchin’ me somethin’ fierce. Not for nothin’, but it’s like gettin’ pulled off by a friggin’ horse. Ay, I’m walkin’ here!’

Ella and Felix stared at him like he’d grown a second head.

‘What? Too much? ’

‘A little bit.’

'Well, I liked it,' Felix said. 'Throw some Jersey in there too. That's where I grew up.'

‘Jesus. Anything else? Maybe I should do a Cockney walk while I’m at it.’

‘Cockney? What’s that?’

‘An area of London where criminals live.’ Luca tried his voice again, this time sounding marginally less like a cartoon wise guy. ‘Any better?’

‘Getting there. Just remember - Jersey's got soft Rs. Like you're too tired to finish the word.’

Luca shook off this new persona and assumed his normal self for a moment. ‘Look, if things get out of hand, I’m just going to start shooting. I shouldn’t need a mask and hair dye when I’ve got a gun on my hip.’

Felix jumped out of his seat. ‘No. Please don’t hurt any of them.’

‘What? These guys are sending you threatening letters and you’re worried about their safety?’

‘I know, but... Arrest them, sure. Just don’t kill any.’

Ella filed that little nugget of concern away for later. It was strange what indoctrination did to a person. She guessed there was an element of Stockholm Syndrome at play too.

‘I’ll try my best. What else do I need to know? I’m only doing this once, so make sure you give me every little detail.’

Felix shifted in his seat, looking like he'd rather be anywhere else. But Ella had to give him credit – he was cooperating, even if it was under duress. Maybe there was hope for him yet.

‘There's a password. You gotta say it to Caleb. The guy on the door.’

‘Okay, what’s the password?’

‘Sanguine.’

‘Sanguine? Seriously?’

‘It's Latin,’ Ella said. ‘Means blood.’

Luca threw up his hands. ‘Fine. Sanguine it is. Then what?’

'Everyone files in. Forms a circle. Eight chairs, always arranged the same way.' Felix sketched the layout with his fingers on the table. 'Ezra stands in the middle. Sometimes, he draws symbols on the floor with chalk. Sometimes he just talks.'

‘About what?’

‘Everything. Nothing. Evolution. Transformation.’

‘Great. What if I have to take my hood down? Or remove this stupid mask? ’

‘No. Members keep their disguises on the whole time. Only Ezra removes his. It’s like a removal of self. Like we’re all just numbers, not humans.’

Ella was beginning to itch. Was this a good idea? She wasn’t sure anymore.

‘In the meetings, I was usually the quiet one. Didn't say much, just kind of nodded along. But you gotta pay attention because Ezra might call on you, ask you something directly.’

‘What do I do if he asks me something specific about you?’

‘He won't,’ Felix said, shaking his head. ‘Me and him weren't close like that. He doesn't know me that well.’

Ella wasn't so sure. From her research, cult leaders made it their business to know everything about their followers. It was how they maintained control and kept people dependent. But she kept her doubts to herself. No need to rattle Luca any more than he already was.

‘And the other members? Will any of them be able to tell that I’m an imposter?’

'Not if you keep your hood up and mask on.' Felix scratched at his wrist, where the cuff had left a red mark. 'Number Three talks a lot. Real philosophical type. Number Five too, but different style. More aggressive. Number Six has a weird tic. Don’t mention it.’

Luca paced the room, decked in a pair of Felix's boots that they'd imported from his house. No detail was too small when you were infiltrating a cult. Luca glanced at Ella with a question in his eyes. She tilted her head towards the door. Luca nodded, then turned back to Felix. 'Sit tight. We'll be right back.'

Ella followed Luca out into the hallway. She closed the door behind them.

‘This is harder than it looks.’ Luca tugged at the mask where it pressed against his nose. The elastic strap had already left a red line across his cheek. ‘You know this is completely insane, right?’

She smoothed his hoody down at the shoulders. Luca was a noticeable few inches wider than Felix, but hopefully the other members would chalk that up to his clothing. ‘If you don’t want to do it, it’s fine. We’ll just take this group down the official way.’

‘We’ve come this far. And if I record everything that goes on, we might get some good circumstantial evidence out of it.’

She studied his face, remembering the farm, the way he'd frozen at the sight of those barns. Yes, they might get some good circumstantial evidence out of it, but she couldn’t put the job before her partner, despite the coldness between them at the minute.

‘You’re a good agent, Hawkins. And an even better liar. If anyone can do it, it’s you.’

‘Thanks. If you hear gunfire, that’s your cue to come running.’

‘You got it. Me and Ross will be waiting outside.’

‘Good.’

‘Are you all ready?’ Ella asked. ‘The fun starts in a couple of hours.’

‘Yup. Just let me work on my accent then we’re good to go.’

Somewhere out there in an abandoned clothing store, eight chairs waited in a circle. Eight masks would gather to discuss mysteries and transformation.

And one of them might just be killing people in the name of ancient wisdom.