Ella's Glock never wavered as she stared down its barrel at Amelia Blackwood. The Alchemist herself, caught like a rat in a trap. The only way out of here was fifty feet down.

‘Show me those pretty hands, Amelia. Nice and slow.’

Amelia's eyes burned with fury hotter than her fiery element. But she complied, raising pale fingers that bore the same flakey skin as her cheeks and forehead. The thick layer of concealer on her face cracked like old paint.

‘You. The bitch from NYU,’ Amelia spat.

‘Got it in one.’ Ella's aim held steady. ‘And since you asked so nice before, I'll answer your question. Female serial killers aren’t changing . They’re the same as ever. Case in point - you.’

Amelia’s gaze darted from one corner to the next. She stole a glance over the railing, down to the concrete floor of the auditorium below. ‘I'm not a serial killer.’

‘Really? Four bodies says different.’

Amelia's lip curled into a. ‘You don't understand. It's not that simple.’

‘Then enlighten me. What's a nice girl like you doing in a cult like this?’

That struck a nerve. Amelia's hands flexed like she wanted to wrap them around Ella's neck. Ella took a few steps closer to her prize. She could put a bullet in her leg right here and now, but there were still a thousand people down below. Ella could vaguely make out Luca directing traffic down there. A stray bullet could be catastrophic.

‘You think you're so smart. You and your profiles, your textbook theories. But you don't know what it's like. To look in the mirror and see a stranger staring back.’

Ella's pulse pounded in her ears. Keep her talking. Buy time for backup. Once enough bodies got here, Amelia would understand that the only way out of here was in the back of a squad car. ‘The scars. That's what this is about.’

‘You think this is about vanity? About looks?’

‘Yes. I think you’re taking after your idol. Hermes Trismegistus.’

‘No. I only found Hermes because I had to.’ Amelia's control slipped. ‘I was normal once. Pretty, even. Then the accident... the chemicals... ’

Something clicked in the back of Ella’s brain. A connection she should have made earlier. ‘The chemicals? You handled sodium thiopental.’

‘Yes I did, genius.’

Understanding smacked Ella around the skull. The sodium thiopental – the very weapon that Amelia had used – was the thing that originally scarred her. She’d turned her trauma into a weapon. There was no such thing as a unique serial killer.

Ella's finger tightened on the trigger, itching to put this rabid dog down. But she needed a confession, not a corpse. She’d begun this investigation because of a compulsion to find a missing person, and now she had to know every little detail of this woman’s psychopathology and motivation. In her peripheral vision, movement flickered. Security guards flanking the balcony, hands on holsters, waiting for the word. Fifty feet below, gawking audience members had caught wind of the altercation in the dress circle.

‘Whatever happens, Amelia, you’re not getting out of here. We’ve got evidence that ties you to four murder victims. We know you tried to frame Ezra. We know you tormented your own brother.’

‘So?’

‘So you’re leaving here in handcuffs. We’ve got guards at every exit.’

Something broke behind Amelia's eyes. The mask of control shattered to reveal something raw underneath. She'd come so close to completing her ritual only to watch it crumble at the finish line. Her hands clawed like she could tear reality to confetti.

‘You think you've won? You haven't stopped anything. Nothing can hold me.’

Then Amelia moved with the liquid speed of a mamba striking. She hit the railing like a fullback slamming the line and swung one leg over. Ella’s gun jerked in her hands.

Her stomach turned three revolutions.

When mission-oriented killers were backed into a corner, they responded one of two ways. All guns blazing or the coward’s way out.

'Don't do it, Amelia. Come back over.' Ella's mind flashed back to the previous day when she'd knocked Amelia's brother off a catwalk in a barn. But this was a lot higher with a more permanent landing. Concrete didn't give much leeway.

‘So shoot me. Shoot me or I jump. ’

Ella's finger tightened on the trigger, but logic overrode instinct. One wrong move and gravity would finish what alchemy had started. Was there a preferable outcome here? Suicide by cop or suicide by concrete?

‘Amelia, there’s nowhere to go. Don't be stupid.’

‘Stupid? Are you serious? I’m a NYU major, top of the class, and all I wanted was to not look like a freak.’ Amelia stabbed her face with her finger.

‘Think about Felix. Your brother. Your dad.’

‘Felix never understood. None of you did.’ Amelia balanced on the thin brass rail like a gymnast on her final routine. ‘The texts were right. Sometimes you have to break something to remake it.’

‘Those texts are ancient. They mean nothing. None of it’s real.’

‘No. The transformation must be completed. As above, so below.’

‘This isn’t your transformation. You’ll die.’

‘Body for soul. Matter to energy. The final sacrifice.’

Ella's brain spun like tires on an icy road. Amelia had the look, that zero-in-the-eyes stare of someone who'd clocked out of reality and punched into the express lane to absolute desperation. Reason was wasted breath. So was negotiation. This bitch was going to jump, and there wasn't a damn thing Ella could do to stop her without getting dragged over the side herself.

So she did the only thing left. The desperate Hail Mary they never taught in hostage training.

She lowered her gun. Held out her free hand, palm up. The supplicant's pose.

‘Amelia, listen to me. It's not-,’

Too slow. Amelia spread her arms like the Dark Angel herself and pitched forward into the abyss.

‘No!’ The word tore from her throat. Ella lunged forward for the railing but Amelia was gone, swallowed by gravity's greedy maw. The Alchemist's last transmutation.

Pandemonium erupted. From security guards, cops, spectators. Shouts and shrieks bled together in a cacophony of horror. Some wit in the audience finally realized they'd gotten more philosophy than they paid for tonight.

But Ella barely heard the din. Her pulse pounded in her skull as she braced for impact. For the wet smack of flesh and bone on unforgiving concrete and a whole load of blood and internal organs to clear up. Ella thought of Marcus Thornton – the victim who’d brought her here in the first place – and how death from a height would be the perfect exclamation point on this sorry case. Five deaths, bookended by sheer drops.

It would have been poetic if not for the fact that the smack of flesh on bone never came.

Impossible.

Ella risked a peek over the ledge.

But the ground below was pristine. No splatter, no messy abstract art. Just a circle of spectators and one pissed-off perp, alive and thrashing in a familiar set of arms.

Luca Hawkins, rookie extraordinaire, had somehow snagged Amelia in midair. Now he grappled with a hundred pounds of spitting, clawing rage as he wrestled her to the ground. A classic Bureau takedown – face to the floor, arm cranked up to the shoulder blades. Crack the joint or crush the will.

Ella gripped onto the handrails as she watched in awe. He must have seen her going for the rail. Must have calculated the trajectory and gotten there in time.

A breathless Luca stood up, planted his foot on Amelia's spine. The rookie had done it again. God knows how he did it, but he always comes through at the right time. Ella wished she had half of his perfect timing.

A circle of spectators had crowded around the show. Luca waved them back, then caught Ella’s eye up in the dress circle.

‘Killer caught, psychic alive,’ Luca puffed loud enough for Ella to hear. ‘That’s what I call a happy medium.’

Ella collapsed into a chair and breathed a sigh of relief.

Game over.