When Hennessy returned with a tray and glasses I commented: 'You say there's nothing of Alice Hollinger's here. Isn't that rather strange?'

Hennessy poured the pale malt into our glasses. 'But why, dear chap?'

'David…' I paced around the sitting room, trying to adjust my mind to this half-sized world. 'We have to assume that she and Sansom were having an affair. It may have been going on for years.'

'Unlikely.' Hennessy savoured the whisky's bouquet. 'In fact, wholly impossible.'

'They died in his bed together. He was gripping her shoes, obviously part of some weird fetishistic game they played. It's enough to make Krafft-Ebing sit up in his grave and whistle. If Hollinger learned of the affair he must have been devastated. Life would have had no meaning for the poor man. He toasts the Queen for the last time and then commits his version of hara-kiri. Five people die. Perhaps Frank, unwittingly, told Hollinger about the affair. He realizes he is responsible, and pleads guilty.' I looked hopefully at Hennessy. 'It might be true…'

'But it isn't.' Hennessy smiled judiciously into his whisky. 'Come into the kitchen. It's hard to think clearly in here. I feel like a character in the Alice books.'

He stepped into the kitchen and sat at the glass-topped table as I prowled around the dainty space with its burnished copper pans and earthenware dishes, niched tea-towels and tissue rolls. Above the stone sink was a notice-board covered with personal miscellanea: holiday postcards from Sylt and Mykonos, pasta recipes torn from a Swedish magazine, and photographs of handsome young men in minuscule swimming thongs lounging on a diving raft or lying side by side on a shingle beach, naked as seals.

Thinking of the young Spaniards in their posing pouches, I asked: 'Was Sansom an amateur sculptor?'

'Not that I know of. Is that part of your theory?'

'These young men – they remind me of the male models in the sculpture classes here.'

'They're Swedish friends of Sansom's. Sometimes they'd visit Estrella de Mar and stay here. He'd take them for dinner at the Club. Charming youths, in their way.'

'So…'

Hennessy nodded sagely. 'Exactly. Roger Sansom and Alice were never lovers. Whatever was going on in that tragic bed had nothing to do with sex.'

'Idiot…' I stared at myself in the Venetian mirror above the pastry board. 'I was thinking of Frank.'

'Of course you were. You're sick with worry.' Hennessy stood up and handed me my drink. 'Go back to London, Charles. You can't solve this thing on your own. You're tying yourself into a mess of knots. We're all concerned that you may actually damage Frank's case. Believe me, Estrella de Mar isn't the sort of place you're used to…'

He shook my hand at the doorway, his soft palm the gentlest of brush-offs. Holding a set of silk ties, Hennessy watched me step into my car like a schoolmaster faced with an over-eager but naive pupil. Annoyed with myself, I set off along the narrow street, past the surveillance cameras that guarded the lacquered doorways, each lens with its own story to tell.

Hidden perspectives turned Estrella de Mar into a huge riddle. Trompe-l'aeil corridors beckoned but led nowhere. I could sit all day spinning scenarios that proved Frank innocent, but the threads unravelled the moment they left my fingers.

Trying to find the Plaza Iglesias, I turned in and out of the narrow streets, and soon lost myself in the maze of alleys. I stopped in a small square, little more than a public courtyard, where a fountain played beside an open-air café. I was tempted to walk to the Club Nautico, and pay one of the porters to retrieve the car. A flight of worn stone steps climbed from a corner of the square to the plaza, but in my present mood I would soon transform it into an Escher staircase.

The café was untended, the owner talking to someone in the basement. Beyond the pin-tables and a television set bearing the notice, 'Corrida, 9-30 p.m.', an open door led to a backyard. I stood among the beer crates and rusting refrigerators, trying to read the contours of the streets above me. A white satellite dish was bolted to an outhouse roof, tuned to the frequency that would relay that evening's bull-fight to the cafe's patrons.

As I stepped past it I noticed the spire of the Anglican church rising above the Plaza Iglesias. Its weather-vane pointed to a penthouse balcony of a cream-faced apartment building on the Estrella de Mar skyline. The silver diamond trembled in the morning air, like an arrow marking a bedroom window on a holiday postcard.

I parked the Renault across the street, sat behind my newspaper and looked up at the Apartamentos Mirador, an exclusive complex built along the high corniche. Balconies freighted with ferns and flowering plants turned the cream facades into a series of hanging gardens. Heavy awnings shielded the low-ceilinged rooms, and a deep privacy layered like geological strata rose floor by floor to the sky.

A decorator's van stood outside the entrance, and workmen carried in their trestles and paints. A pick-up truck passed me and pulled in behind the van, and two men stepped from the driving cab and unloaded a jacuzzi's pump and motor unit.

I left my car and crossed the road, reaching the entrance as the men climbed the steps. A uniformed concierge emerged from the lobby, held open the doors and beckoned us through. An elevator took us to the penthouse level. Two large apartments occupied the floor, one with its door held open by a wooden trestle. I followed the workmen into the apartment, and made a pretence of checking the electrical wiring. Wide balconies surrounded the rooms, from which all furniture had been removed, and decorators were painting the walls of the split-level lounge.

Ignored by the workmen, I strolled around the apartment, already recognizing the art deco motifs, the strip lighting and porthole niches. I assumed that the apartment had been leased by the makers of the porno-film, who had now fled the scene. I stood in the hall, sniffing the scents of fresh paint, solvents and adhesive, while the men with the jacuzzi motor lowered it to a bathroom floor.

I stepped into the master bedroom, which overlooked the harbour and rooftops of Estrella de Mar, and closed the mirror- backed door behind me. A white telephone rested on the floor, its jack pulled from the socket, but otherwise the room was almost antiseptically bare, as if sterilized after the completion of the film.

With my back to the mantel, I could almost see the bed with its blue satin spread and teddy bear, and the Hollingers' niece with her wedding dress and sinister bridesmaids. I framed my fingers around my eyes, trying to place myself where the camerawoman had stood. But the perspectives of the room were elusive. The positions of windows, balcony and the mirror-door were reversed, and I guessed that the rape had been filmed within a second mirror, reversing the scene in an attempt to disguise the participants.

I unlatched the door on to the balcony and looked down at the spire of the Anglican church. Beyond it the satellite dish had moved a few feet to the right, searching the sky for its bull-fight, and the weather-vane pointed to the rear door of the café.

A woman's voice, more familiar than I wanted to admit, sounded from a nearby window. Beyond the glass-walled stairwell was the balcony of the apartment that shared the penthouse floor. Leaning over the rail, I realized that the porno-film had been shot in one of its bedrooms, the symmetrical twin of the one in which I stood, from where the weather-vane and satellite dish would be exactly aligned.

While the woman's laughter continued, I peered around the stairwell. Twenty feet from me, Paula Hamilton leaned against the rail, face raised to the sun. She wore a white surgical coat, but her hair was unpinned and floated on the wind in a bravura display. Bobby Crawford sat beside her in a deck-chair, pale thighs emerging from his dressing-gown. Without inhaling, he touched his lips with the gold tip of his cigarette and watched the smoke sail across the gleaming air, smiling at Paula as she remonstrated playfully with him.