"Tell me about Carlota Bruner," he said.

Instantly the atmosphere changed. She stubbed out her cigarette and looked at him sharply. The gold flecks in her eyes were gone. "Where did you get that postcard?"

"Somebody put it in my room."

Macarena stared at the yellowed photo of the church. She shook her head. "It's mine. From Carlota's trunk. You can't possibly have it."

"Well, I do." Quart turned the postcard over. "Why isn't there a postmark?" he asked.

Her anxious eyes went from Quart to the postcard and back. He repeated the question. She nodded but didn't answer immediately.

She picked up the card and examined it. "Because it was never posted," she said. "Carlota was my great-aunt. She was in love with Manuel Xaloc, a poor sailor. Gris said she told you the story…" Macarena shook her head, as if denying something or overcome by sadness. "When Captain Xaloc emigrated to America, she wrote him a card or letter almost every week for years. But her father the duke, my great-grandfather Luis Bruner, prevented the letters from getting through. He bribed the post office employees. In six years she didn't receive a single letter, and we believe he didn't either. When Xaloc came back for her, Carlota had lost her mind. She spent days at the window, watching the river. She didn't recognise him."

Quart pointed at the card. "And what happened to the letters?"

"Nobody dared destroy them. They ended up in the trunk where all Carlota's things were stored after she died in 1910. I was fascinated by the trunk when I was a child: I'd try on the dresses, the jet necklaces…" Quart saw the beginnings of a smile on her lips, but her eyes returned to the postcard and the smile vanished. "In her youth, Carlota went with my great-grandparents to the Universal Exposition in Paris, and to the ruins of Carthage in Tunisia. She brought back old coins. There are also boat timetables and hotel brochures, old lace and muslins. A whole life. Imagine the effect it all had on me when I was ten or eleven. I read every single letter. My great-aunt seemed such a romantic character. She still fascinates me."

She was running a fingernail on the tablecloth, around the postcard. She stopped, thoughtful.

"A moving love story," she said, looking up at Quart. "And like all moving love stories it had an unhappy ending."

Quart said nothing, wanting her to go on with the story. But she was interrupted by the waiter, who brought her credit card receipt. Quart noticed her signature: nervous, full of angles as sharp as daggers. She gazed at the cigarette stub in the ashtray, lost in thought.

"There's a beautiful song," she went on after a moment, "sung by Carlos Cano, with lyrics by Antonio Burgos: 'I still remember that girl and her piano in Seville…'It makes me want to cry every time I hear it… Do you know there's a legend surrounding the story of Carlota and Manuel Xaloc?" Her smile was uncharacteristically shy and indecisive. Quart realised that she believed in the legend. "On moonlit nights, Carlota reappears at her window while her lover's ghostly schooner sails down the Guadalquivir." She leaned forward, and again Quart once again felt she was too close. "When I was little, I spent whole nights looking out for them! And once I saw them. She was a pale shadow at the window. And down on the river, in the mist, the sails of an old ship slid slowly out of sight."

Macarena fell silent and leaned back in her chair. The distance between them returned. "After Sir Marhalt," she said, "my second love was Captain Xaloc…" Her look was provocative. "Do you think it's an absurd story?"

"Not at all. Everyone has ghosts."

"And what haunts you?"

Quart smiled with a distant look in his eye. Wind and sun, and rain. The taste of salt in his mouth. Memories of a poor childhood, of knees always dirty, and him watching the sea for hours. His youth had been intellectually confined, dominated by discipline, with some happy memories of companionship and brief moments of satisfied ambition. Solitude at airports, over a book, in a hotel room. And fear and hatred in the eyes of other men: the banker Lupara, Nelson Corona, Priamo Ferro. Corpses – real and imaginary, past and future.

"Nothing special," he said coolly. "Like you, ships that set sail never to return. And a man. A Knight Templar in chain mail leaning on his sword, in a desert."

She looked at him strangely, as if seeing him for the first time. She said nothing.

"But ghosts," added Quart, "don't leave postcards in hotel rooms."

Macarena touched the card still lying on the table with the writing face up: I come here to pray for you every day… Her lips moved silently as she read the words that never reached Captain Xaloc. "I don't understand," she said finally. "The card was at my house, in the trunk with the rest of Carlota's things. Somebody must have taken it from there."

"Who?"

"I have no idea."

"How many people know about the letters?"

She thought hard. "No," she said after awhile. "It's too absurd."

Quart reached with his hand and saw Macarena shift back in her chair, almost as if in fear. He turned over the card and showed her the photograph of the church. "There's nothing absurd about it," he said. "This is the place where Carlota Bruner is buried, near Captain Xaloc's pearls. The church that your husband wants to demolish and that you're defending. It's the reason for my presence in Seville, because two people have died there." He looked up at her. "A church that, according to a mysterious computer hacker we've called Vespers, kills to defend itself."

She began to smile, but the smile faded to preoccupation. When she spoke, surprisingly, the tone was more annoyed than anxious. "Don't say that. It scares me."

Quart watched her turn the plastic lighter over in her fingers. He felt that Macarena Bruner was lying. She wasn't the kind of woman who scared easily.

Since Vespers' appearance a week ago, Father Ignacio Arregui and his team of Jesuits – all computer experts – had been watching the central Vatican system in twelve-hour shifts. It was now ten minutes to one in the morning, and Arregui went to get coffee from the vending machine in the corridor. The machine accepted his hundred-lire coin but returned only an empty cup and a little heap of sugar. The Jesuit cursed, glancing out of the window at the Belvedere Palace. He searched his pockets for more coins and made a second attempt. This time he got a coffee but no sugar. Luckily the previous cup had remained upright in the dustbin so he used the sugar from that to sweeten his drink. He went back to the computer room. "Here he is again, Father."

Coocy, the Irishman, was staring excitedly at a screen. Another young Jesuit, an Italian called Garofi, was desperately typing at a second terminal.

"Is it Vespers?" asked Father Arregui. He stared over Cooey's shoulder, fascinated by the blinking of the red and blue icons and the vertiginous speed with which the files checked by the hacker scrolled past on the screen. The hacker's movements were shown on one monitor while, on another, Father Garofi tried to track him down.

"I think so," answered the Irishman. "He knows the way and he's going really fast."

"Has he got to the SSs?"

"Some of them. But he's clever: he's not falling into them." Father Arregui took a sip of coffee. It scalded his tongue. "Damn him," he said.

The SSs – Sadducean Snares, as the team had nicknamed them -were like nets at the mouth of a river, in which hackers were snared or at least revealed information that made it possible to track them. The traps that had been laid for Vespers were sophisticated electronic labyrinths that forced an intruder to show his hand.

"He's looking for INMAVAT," said Cooey.

There was again a hint of admiration in his voice. Frowning, Father Arregui glanced at the young man. It was to be expected, he thought as drank his coffee. He couldn't help feeling professional excitement himself, when he saw a member of the computer fraternity doing his stuff so stealthily and cleanly. Even if Vespers was a criminal who was giving them all sleepless nights.