Even with the sirens howling, and some very aggressive driving on Dima's part, it takes us almost ten minutes to reach the front of the theater. The entrance doors are closed, and the sumptuous foyer is silent except for the sotto voce chatter of the front-of-house staff, who surround us officiously as we enter and then stand back respectfully when Tikhomirov identifies himself. He makes a call, and thirty seconds later two FSB officers in dress uniforms hurry down the central staircase, salute, and assure him that all is well, and that all the appropriate security measures are in place. Tikhomirov looks unconvinced and summons one of the theater managers to take us into the auditorium.

We're led up a short flight of steps to a horseshoe-shaped corridor with numbered doors. "These are the lower boxes," the manager explains, opening the furthermost door. "And this box is always kept in reserve. You're welcome to use it for the duration of the performance." He withdraws, as unctuous as a courtier, and I look about me. The box is tiny, and upholstered in scarlet. Tchaikovsky's music soars from the orchestra pit, while on stage a Christmas party is in progress, with the dancers in Victorian-era costumes. It's all so captivating that I momentarily forget why we're here.

"Wait here," Tikhomirov whispers. "Sit down."

Beside me I sense Tikhomirov relax. On the far side of the stage, in a larger, much grander box, all swagged velvet and gold tassels, sit Stechkin and Loy. Stechkin looks inscrutable, Loy appears to be asleep.

He's back two minutes later. "It's all fine. There are two armed officers outside the presidential box. Nobody can get in."

The first act comes to an end, the curtain falls, and the house lights come up. Opposite us Stechkin stands and guides Loy out of sight.

He rolls his eyes and smiles wearily. "No shit."

"I'm sure they've got plenty to talk about."

I nod. I'm shattered. I'd love to close my eyes and drown in the music, but part of me is wondering, as Tikhomirov is surely wondering, where Oxana is. If Charlie and I were the diversion, what was the plan?

We remain in our seats. Tikhomirov keeps a phone connection open to his officers, but they have nothing to report. He begins to tap his foot and, eventually, he stands. "Shall we walk?"

"There's a private reception room attached to the presidential box," Tikhomirov says. "They won't be disturbed there."

"Sure."

"Anything wrong?" Tikhomirov asks.

We leave the box and make our way around the long, curved corridor. It's slow going; the passage is narrow and crowded, and several of the patrons are elderly. Halfway round we encounter the house manager, who is speaking irritably into his phone.

"Where?"

"Show me," says Tikhomirov.

"In the ladies' restroom, downstairs."

"Nothing unusual. A woman has locked herself in a toilet stall and passed out, apparently drunk."

"Take us there, please. Hurry."

Anxious to oblige, the manager leads us down to the foyer, where a harassed-looking attendant is waiting.

The restroom is crowded with female patrons, through whom Tikhomirov barges unceremoniously. A bell sounds over the theater's PA system and a voice announces that the curtain will rise on Act 2 of The Nutcracker in five minutes. When we reach the locked stall, Tikhomirov puts a broad shoulder to the door and breaks the lock. Inside, a young woman is slumped on the floor. She looks well off, with fine-boned features, little or no makeup and an expensive haircut. As the manager and I hover behind him, Tikhomirov puts his nose to her mouth, and rolls up one of her eyelids. Over the loudspeaker, the three-minute bell sounds.

"No," I say, truthfully. "I've never seen her before."

"Well, she's not drunk, and this isn't an overdose." He rifles through her pockets. "And what's more, she hasn't got any bag, money or identifying documents on her. Do you recognize her?"

What I don't tell Tikhomirov is that the clothes the woman is wearing, the black jeans, gray sweater, and gray-black Moncler camouflage jacket, are identical to those Oxana was wearing when she left the building this morning. I pray that I don't look as sick and faint as I feel.

"When?"

The one-minute bell sounds and Tikhomirov frowns. "What was that you said to me earlier?"

"That they… had plenty to talk about?"

"Ten minutes ago. About Stechkin and Loy."

"Yes. Yes!" He gets to his feet, ignoring the unconscious woman and the manager, and runs for the exit, dragging me after him. "Come on, Eve. Run."

We tear through the gilded foyer, up the stairs, past ushers and program sellers, and back into the corridor serving the boxes. It's almost deserted now; all the patrons have taken their seats for Act 2. At the right-hand end of the corridor, two bulky FSB officers stand outside the door to the presidential anteroom and box. They salute when they see Tikhomirov.

"Never mind that," Tikhomirov barks. "Has anyone come out?"

"No one's gone in, General," one of them says. "Not a soul."

"Only the interpreter, sir."

"Sweet Jesus. Open the doors."

The four of us burst into the anteroom. It's bright scarlet with a ceiling of tented silk. There's a drinks table, holding open bottles of champagne and malt whisky, and three silk-upholstered chairs. Two of these are empty, the third holds the seated body of Valery Stechkin. He's dead, his neck wrenched unnaturally sideways, and his mouth gaping in a horrible simulacrum of pleasure. The body of the American president, meanwhile, has been arranged in a kneeling posture in front of his Russian counterpart. Loy's neck is also broken and his head has been positioned, face down, in Stechkin's crotch. For several long seconds the four of us stare, incredulous, at the last and greatest work of the artist formerly known as Villanelle.

"Find her," Tikhomirov whispers to the two men. "Find the fucking interpreter."

He closes the door on the dead presidents, pulls out his phone and starts giving orders. Other FSB men arrive at a run and are dispatched around the building. After a few minutes Tikhomirov lowers his phone and stares at me. "Eve, you need to go. Find Dima. He's in the car outside. He'll take you somewhere safe. Go now."

It's like walking in a dream, or a nightmare. The corridor seems to last forever, my steps noiseless on the scarlet carpet. As I step out onto the mezzanine floor the orchestra is playing "The Waltz of the Flowers." My parents had a scratchy old record of The Nutcracker.

Then there's shouting, as six FSB men burst into the foyer from the direction of the orchestra stalls. At their center, writhing and kicking, is a female figure in a dark suit. It's Oxana and she's fighting for her life. A rifle butt smashes into her head but she fights on, her face bloody, teeth bared like an animal, and with a furious twist of her body manages to wriggle out of the suit jacket that two of the men are holding and sprints for the main door. She makes it, and hurtles down the steps toward the square. Very calmly one of the FSB men steps into the open doorway, raises his rifle and fires an aimed burst. The rounds hit Oxana between the shoulders -- spots of red on the white shirt -- lifting her momentarily before pitching her onto her face in the wet snow. I try to run to her, screaming now, but my feet won't carry me, hands hold me back, and all that I see is the dark, unfurling flower of her blood.

Of what follows, my memory's fractured. I remember being bundled into a vehicle by men carrying guns, and driven fast through the city. I remember it being very cold when we reached our destination, and being hurried across a courtyard and up a flight of stairs into a small room with an iron bed. I remember letting go. Submitting, finally, to the knowledge that I'm breaking apart.

When I finally start to weep, I can't stop.

It's not only Oxana, although it will always be only Oxana. It's the things I've seen and done. I followed her into the mir teney, the shadow world, not realizing that I couldn't survive there, that unlike her I couldn't breathe its poisoned air. I remember, so clearly, the sensation of riding away with her on the volcano-gray Ducati. Of fitting myself to her back, of holding her tight as we flew into the night. I'd never encountered anyone so dangerous, or so lethally reckless, but she was the only person in the world with whom I felt safe. And now that she's gone, there's nothing left of me.

Oh my love. My Villanelle.