A necklace of tail lights arched across the skyline like a twisted rainbow. No two pairs were quite the same. Red was not always red, but perhaps a shade of orange, a garish green or even blue. Here and there the carnival spin of a twirling amusement flashed in a rear window to alleviate the boredom, coloured lights bursting like tiny explosive charges. Many vehicles showed no lights at all, either because they were defective or because their drivers found them an unnecessary expense. Makana had had plenty of time to study the subject. Years in fact, and tonight the Datsun had been stuck in traffic for what felt like hours but was probably only about forty-five minutes. They were now suspended in mid-air on the 6 October flyover in Abbassiya. Like upraised horns, the twinned minarets of the Al Nour Mosque rose up alongside them.

The whirling carnival lights around the rear window of the minibus ahead of them were a distraction that ticked away in the back of Makana's head, as was Sindbad's constant stream of earthy comments and philosophical insights. The real focus of his attention was a black car just ahead of them on the right. It was quite a distinctive-looking vehicle. Old. Makana guessed at least thirty years. The first time he had seen it he had had trouble identifying it.

'What is that?'

'That, ya basha?' Sindbad licked his lips in anticipation, always pleased to show off his knowledge. 'That is Benteley. English car. Very good quality, from the old days of the Ingleezi.'

It was a source of wonder to Makana where Sindbad ever came up with such nuggets of information. He never seemed to read anything but the sports pages and yet a layer of information, a seemingly random sample of obscure and unrelated facts, had built up in his head, like a sandbank deposited in the Nile over centuries. It could hardly be said that he was a connoisseur of automobiles, since he was content to drive around in this well-beaten bucket of a Datsun, yet some part of him aspired to the craftsmanship and quality of an entirely different class of car.

The distinctiveness of the Bentley made it a little easier to follow. Tonight the sole occupant of the car was a small, compact man, who wore a set of expensive, ill-fitting and rather worn suits. Short-legged and paunchy, he cut an awkward figure who looked as though he had dressed in a terrible hurry. His shirt collars were never straight, his tie was badly knotted. His name was Magdy Ragab, a wealthy and highly respected lawyer in his late fifties. His dull appearance matched his daily routine. For almost a week now Makana and Sindbad, alone or together, had followed the lawyer as he was chauffeured from his home in Maadi to his office downtown and back again. He visited the legal courts, briefly, ate lunch at his desk and worked long hours, often not finishing until nine or ten at night. It was eight thirty now, which was early for him to be heading home. The cars ahead of them slid forward, bringing them to within two cars of Ragab's Bentley, the right-hand lane having not moved. Sindbad cleared his throat, which suggested he had something on his mind. In anticipation, Makana lit a cigarette.

'How much longer do you think she will need to decide his innocence?'

Sindbad's question implied their subject was innocent. Proof was always hard to find in such matters. According to Islamic jurisprudence three witnesses were required to prove adultery, a demand that had always struck Makana as a neat way of sidestepping the issue. After all, what were the chances of locating three people willing to swear a couple had been engaged in sexual relations? But of course it never went that far. Guilt by association. Two people seen talking together was often all the evidence needed to condemn them. In a society preoccupied with purity, sex became an unhealthy obsession. Displays of physical affection were frowned upon in public, even between married couples, which didn't make Makana's job any easier. How do you prove infidelity? The usual signs were gifts, clothes, a car, an apartment where they could meet in secret. For a man, it was possible to engage another woman in an informal contract of marriage without too much difficulty. It was harder for women and the consequences were harsher. Many husbands didn't care too much about evidence. They were only too happy to apply their own brand of justice, which was often less forgiving than the courts might be. The mere suggestion of infidelity could ruin a woman's reputation. Often such cases ended in an impasse. The person who suspected their spouse of infidelity allowed the investigation to go on until they decided enough was enough. Patience ran out, or money, or nerve. Then it could go either way. Makana had, on occasion, been summoned to bear witness before an impromptu hearing in the presence of a judge, but that was rare, and even then inconclusive. Men responded predictably when confronted with evidence against them. Stringent denials on the heads of their mother and children and anyone else they could think of. Those not prepared to swear their innocence inclined to violence. Grown men hurling themselves across the room to try and strangle their wives for having spied on them, oblivious to the people around them, let alone the judge.

What Sindbad was really asking was how much longer they could expect Mrs Ragab to pay them to follow her husband around. They had seen no evidence of infidelity on his part. In Makana's view, Mrs Ragab would probably never be fully convinced that her husband was not planning to desert her for someone else. She was overbearing and difficult to deal with. Certainly, she did not give the impression of being the kind of woman to turn a blind eye to her husband's errant behaviour. In her imagination perhaps there would always be a younger woman somewhere waiting for Ragab to come to her. All Makana could do was report back that so far Ragab's behaviour was about as normal as you could hope for.

The Datsun had slid forward another few metres to where it was almost parallel with the Bentley, bringing Makana to the point where he was sitting alongside Ragab. Turning his head, he glanced across. The lawyer sat staring ahead at the two rows of cars that rose upwards ahead of them like an illuminated path to the stars. What was going on in his mind? For the first time in a week he had broken with routine. For the first time he was heading in an unexpected direction. And he seemed preoccupied, glancing at his watch and tapping the steering wheel impatiently. The right-hand lane began to move. As it did so, Ragab glanced sideways. His eyes met Makana's. It was only for a fleeting moment, but it was probably enough.

'Better change lanes,' Makana said.

Since he had begun to work for him on an irregular basis a few months ago, Sindbad had learned the futility of objecting to Makana's requests, no matter how unreasonable they appeared. He still had to fight the reflex to protest, but he now knew that trying to convince Makana to see the world the way most people did was like trying to make the Nile flow the other way. Sooner or later you had to accept it wasn't going to happen.

'Hadir, ya basha,' he muttered, swinging the wheel to cut into the next lane, causing consternation and some hooting. Makana could see Ragab tilting his head to watch them in the rear-view mirror. If he didn't already realise he was being followed it wouldn't take long at this rate. The switch to the right lane proved to be a wise move. Ahead of them the cars were moving, filing past a stalled minibus whose passengers were standing around. Some admired the view, lighting cigarettes as if they were on an excursion to an exotic planet, oblivious to the discordant serenade from the cars stacked up behind them. Others observed the driver and his young assistant, no more than a boy, as they knelt behind the vehicle and rapped optimistically on the motor with a hammer, as if hoping to scare it back into life.

'Stay close to him,' Makana warned, as his resistance caved in and he reached again for the packet of Cleopatras in his jacket pocket. Something told him they didn't need to be too careful. Ragab had almost looked right through him.

Once off the overpass the traffic resumed its usual insane dance, cars hurling themselves into the fray with reckless abandon. Makana was reminded once more that he was still a stranger here, even after all these years. The Khartoum he had grown up in was really no more than a rural backwater compared to this. Sparsely populated with cars, there always seemed to be enough room to get around at a leisurely pace. The truth was that he preferred Sindbad do the driving, despite the added expense, if only because it left him free to think.

The Bentley slid away from them, passing swiftly through the streets. The dazzle of bright lights reflected in its shiny surface as it sped past the window displays, the flashing neon, and startled mannikins. Bulbs swarmed into arrows, names, invitations: Rahman Fashions, Modern Stylish, Happyness, BabyBoom. A polyglot babel of movie titles, brands, logos, all swimming together in the fluorescent glow like a form of delirium. Then the lights cut away and the Bentley flitted off beneath the trees, slipping into the dark like a moving shadow.

'He's not taking his usual route,' Sindbad announced, speaking Makana's thoughts aloud. They had turned west, towards the river instead of continuing south in the direction of Maadi. A few minutes later they found themselves doubling back, travelling again in the direction of downtown along the Corniche. Ahead of them the big car pulled in to the side of the road.

'Slow down as you go past him and let me out up ahead,' said Makana. When they rolled to a halt under a tree he indicated for Sindbad to stop. 'Wait for me here,' he said. Then he got out and walked back along the busy road.

The Bentley was parked in front of an ugly modern building with a smooth façade that stood out against the lower, more aged apartment blocks on either side. The car was in an area marked off from the road for visitors by an arrangement of chains and metal posts. Makana watched as Ragab ignored a greeting from a uniformed doorman who rushed eagerly about securing the Bentley in place. Makana entered a lobby that ran straight through the building from front to rear. Two lifts stood on either side. When Ragab stepped inside one, Makana followed suit. He could have played safe and waited in the lobby, but by now he was fairly confident that Ragab was preoccupied enough not to notice him. Moving past, Makana stood quietly in the corner behind the other man. Ragab stared at the floor, oblivious of the world around him. On the eighth floor the doors pinged open and Makana hesitated only for a second before following Ragab out. To the left were a set of glass doors on which the words Garnata Health Clinic were painted. The woman on the reception desk glanced up and, when Makana pointed discreetly at the rapidly disappearing Ragab, went back to her work.

The clinic was quiet, modern and empty. At the far end of the corridor lay a waiting area complete with a view over the busy road; beyond that lay the dark gleam of the river and the lights of Dokki on the other side. Ragab had continued down another corridor to the right. Halfway down he entered a room on the left. Makana sat down and picked up a magazine filled with pictures of smiling celebrities he had never set eyes on in his life. The only other person in the waiting area was a man with a mottled head and a tube going into his arm. His nose and mouth were covered by a transparent mask. Beside him stood a tall canister of some kind of gas. Makana flicked through the magazine. After a time a male nurse appeared and wheeled the other man away without a word. When they had gone, Makana got up to stroll over and take a look in the direction of the room into which Ragab had disappeared. The two men almost collided.

Ragab stepped aside without looking up. Makana was fairly certain that he was crying. Tossing the magazine into the heap on the coffee table Makana made his way down the corridor to the room Ragab had emerged from. It was slightly ajar. He could hear nothing from within so he knocked lightly and when there was no reply he pushed the door gently open and stepped inside.