'Miguel…' I walked up to him, a hand raised in greeting. 'I came to the house with Inspector Cabrera. I'm Frank Prentice's brother. I wanted to talk to you.'

He lowered his eyes and stared at the pit, then turned on his heel and walked back to the gate. He closed it behind him and moved quickly down the steps, shoulders hunched as he disappeared into the garage.

'Miguel…?'

Irritated by the persistent hang-glider, I looked down at my feet. Two silver coins lay in the charcoal-covered soil, pieces of silver presumably intended to express the chauffeur's contempt for the family that had murdered his employers.

I knelt down and prodded the coins with my fountain pen, then realized that I was touching a pair of car keys, linked together by a small metal chain and partly buried in the earth. Without thinking, I accepted that the keys were those of the Bentley, dropped by the chauffeur as he waited for me. I wiped them and brushed away the dirt, ready to return them to Miguel. But the Bentley's engine was turning, vapour rising from the exhaust, and the keys had no doubt been dropped by a member of the police forensic team. I held them in my hand, trying to identify the make of car, but the flat chrome was unmarked. Already I suspected that the keys might belong to the arsonist, lost or forgotten by him when he retrieved the buried flasks.

The hang-glider hovered over my head, its steel guy-ropes singing in the air. The pilot's gloved hands clasped the control bar, as if reining in a winged horse. The craft banked steeply and dived across the orchard, its left wing nearly striking my face.

I crouched among the burnt-out trees as the glider circled above me, ready to make another pass if I attempted to reach the gate to the Hollinger house. Head lowered, I ran across the ashy soil, deciding to make my way down the hillside that lay beyond the outer wall of the estate. Again the glider soared forwards, riding the thermals that swept up the open slopes. The pilot seemed unaware that I was scrambling and sliding beneath him, his eyes apparently fixed on the waves rolling towards the beaches of Estrella de Mar.

Below me appeared a line of villas built among the eucalyptus trees that lay beyond the lower boundary of the Hollinger estate. The rear gardens and courtyards were protected by high walls, and from the alarmed expression of a maid watching me from a second-floor balcony I knew that none of the residents would come to my aid, let alone admit me to the shelter of their gardens.

Covered with dust and ash, I stumbled towards the rear wall of the Protestant cemetery. The thoughtless pilot had returned to the summit, circling before he set off in a steep dive towards the landing beach below him.

A stone refuse tip stood by the rear gate of the cemetery, filled with dead flowers and faded wreaths. I wiped my hands on a bouquet of cannas, trying to squeeze the last moisture on to my raw palms. Brushing the ash from my shirt, I pushed back the gate and set off through the graves.

Apart from a single visitor, the burial ground was empty. A slim man in a grey suit stood with his back to me, clasping a spray of lilies and fern that he seemed reluctant to lay on the memorial stone. When I passed the burial plot he turned and almost flinched from me, as if I had caught him at a moment of guilty thought. I recognized the mourner shunned by almost everyone at the funeral of Bibi Jansen.

'Dr Sanger…? Can I help you?'

'No… thank you.' Sanger was feeling the face of the headstone, his gentle fingers touching the letters incised in the polished marble. The silver stone was the same colour as his hair and suit, and his eyes seemed even more melancholy than I remembered them. At last he laid the lilies against the stone and stood back, a hand on my elbow.

'Well… how does that seem?'

'It's a fine memorial,' I assured him. 'I'm glad everyone rallied round.'

'I ordered it myself. It was the right thing to do.' He offered me his handkerchief. 'You've cut your hand-shall I look at it for you?'

'It's nothing. I'm in a hurry. A hang-glider attacked me.'

'A hang-glider…?'

He searched the sky, and followed me when I set off for the entrance. I unlatched the gates and stepped into the street, steadying myself against the roof of a parked car. I tried to read the contours of the hillside. The Citroen was at least half a mile away, parked on the slopes to the east of the Hollinger estate.

I waited for the next taxi to deliver mourners to the cemetery, then filled my lungs for the tiring walk. Fifty yards from me, outside the entrance to the Catholic cemetery, a motor-cyclist in black leathers and helmet sat astride his machine, a scarf over his face. His gauntleted hands gripped the handlebars, and I could hear the soft mutter of the machine's exhaust. The front wheel turned fractionally and seemed to point towards me.

I hesitated before stepping from the kerb. The road ran past the secluded villas, and then dipped from sight as it descended towards Estrella de Mar. Hovering in the air like an observation craft was the hang-glider, its wings placed between me and the setting sun, so that the fabric glowed like the plumage of a burning bird.

'Mr Prentice…?' Dr Sanger touched my arm. His face was composed now that he had left the cemetery. He pointed to a nearby car. 'May I give you a lift? It might be safer for you…'

'You've been favoured,' I told Sanger as we rolled up the drive towards his villa. 'Apart from New York, that's the most impressive collection of graffiti I've ever seen.'

'Let's be charitable and call it street art. But I'm afraid it has other intentions.'

Sanger stepped from his car and surveyed the garage doors. Graffiti covered every inch of the steel panels, an aerosolled display of fluorescent whorls and loops, swastikas and threatening slogans that continued across the window shutters and front door. Repeated cleanings had blurred the pigments, and the triptych of garage, windows and door resembled the self-accusing effort of a deranged Expressionist painter.

Sanger stared wanly at the display, shaking his head like the distracted curator of a gallery forced by the pressures of fashion to exhibit works for which he had little sympathy.

'I suggest you rest for a few minutes,' he told me as he unlocked the door. 'A taxi can take you back to your car. It must have been an ordeal for you…'

'It's kind of you, Doctor. I'm not sure if I was in any danger. I seem to have a knack for tripping over my own feet.'

'That hang-glider sounded threatening enough. And the motor-cyclist. Estrella de Mar is more dangerous than people think.'

Sanger ushered me into the hall, watching the empty street before closing the door. With a faint sigh, a mix of relief and resignation, he stared at the bare walls, criss-crossed by the shadows of the steel grilles over the garden windows, each a dark portcullis. Our silhouettes moved across the bars, figures in a pageant of convict life.

'It reminds me of Piranesi's Carceri – I never thought I'd live inside those strange etchings.' Sanger turned to examine me. 'Were you in danger? Very possibly. Crawford likes to keep the pot stirred, but sometimes he goes too far.'

'I feel better than I thought. As it happens, that wasn't Crawford in the hang-glider. Or on the motor-cycle.'

'His colleagues, I dare say. Crawford has a network of sympathizers who know what he wants. I assume they were teasing you. All the same, be careful not to expose yourself, even if you are Frank's brother.'

Sanger led me into a lounge overlooking a small, walled garden almost entirely filled by a swimming pool. The long room was furnished with two armchairs and a low table. Books had once lined the walls, but now filled a collection of cardboard cartons. The air seemed motionless, as if the windows and doors to the garden were never opened.