With her hands around his hips, she felt odd sitting on the back of the motorbike. And none too safe, either, as they weaved through the narrow streets – her rucksack strapped crossways on the pillion, her hair streaming out behind. There was only one helmet, and it was too big for her when she tried it. In the end they both rode bare-headed; he tied the helmet to the pillion with little bungees.

She had thought a lot about seeing him again, conjuring the figure on the beach in her mind during their exchange of emails. Reality didn’t disappoint, and her senses quickened when she saw him there waiting for her at the airport, smiling and bronzed, with the helmet under his arm. As they went out to his bike in the sunlit car park, all her smoky imaginings of what this moment would be like kindled into flame, springing spontaneously in the heart. Yet behind the glow of warm feelings, there was a warning voice telling her to be prudent, to keep her self-possession.

He took her for coffee at the Livingstonia Hotel. Two cannons at the entrance door. Very British. Very colonial. Inside was a weary snooker table and an age-dimmed indication in wood relief: The Ladies’ Powder Room. Two things rescued this run-down and slightly sad establishment, where even the hunting trophies looked mournful, as if the animals had known they were going to be killed. The first was a wonderful balcony, opening out to the sea, high above the rusty, corrugated-iron roofs of the town. The second was an old library, full of red and brown hardback English books with titles like Tales from the Mysterious East and Memoirs of the Boer War.

‘Ray would like it here,’ she said, as they peered through the glass of the dusty cabinets. The Effect of Tropical Light on the Skin of White Men. Fortune My Foe.

‘Who’s Ray?’

‘A guy at the embassy. He’s kind of a bookworm.’

‘Right,’ said Nick, nodding.

She wondered if he suspected Ray was a rival for her attentions, which was crazy, considering, but then he wouldn’t know. Yet the moment had already passed at which to put him at his ease… in any case, the insistence would have created too obvious an invitation.

She wasn’t sure if she herself liked Stone Town. Its crumbling coral houses seemed slightly hostile. Especially the former residence of Tippu Tip. Nick said Tippu Tip was a famous slave trader who had helped Livingstone and Stanley make their explorations. Now a private house, it had a large carved front door, in front of which sat an old bearded man in turban and robes. On the steps beside him, a noisy crowd of children were playing with wooden models of aeroplanes and cars. They were imitating the sounds of the engines, careening the models through the air close to the old man’s face. He remained unmoved.

They left the old man and snaked through the busy streets, under carved wooden balconies. Electricity cables were looped from house to house, and she worried they might hit one. From the doors of the Indian curio shops, some of which were studded with brass knobs or lines of cowrie shells, tourists emerged sporting old silver bracelets or cradling antique nautical instruments. She also saw basketfuls of crabs and shrimps, sitting in the open sunlight, their contents still twitching, and street vendors grilling chunks of squid or lobster on wooden skewers over charcoal fires. Everywhere was the smell of fish and spices and flowers. At one point the bike sped down a street whose surface was covered with hibiscus petals. Miranda guessed there must have been a wedding there, or some other kind of feast.

Further on, he stopped to show her some iron rings where slaves had been chained.

‘Is this where they were sold?’ she asked him, staring at the scarred old metal.

‘Don’t think so,’ he said, putting out a foot to steady the bike. ‘I heard a church was built on the site of the old market. I guess they just… kind of waited here.’

There was a pause during which she was conscious of his body in front of her, between her knees, and the hair on the nape of his neck. He kicked the pedal and restarted the engine.

The next place they visited was the Old Arab Fort, which a sign said had been built between 1698 and 1701. It was a large stone building with medieval-style battlements. It now contained a restaurant.

Over his shoulder, Nick said: ‘And Leggatt – he’s a British guy I met, maybe we’ll go see him – told me the Arabs built that on the site of a Portuguese church, so I guess it’s a case of what goes around comes around.’

They also visited an edifice called the House of Wonders. A large balustraded building with a clock tower and lots of tiers and fretwork, it had once been the Sultan’s ceremonial palace.

‘There’s a story that the skull of a slave was buried under each of those columns,’ he informed her, as they dismounted. ‘It’s going to be a museum, once the government finds the money to do it up.’

‘Everything here seems to be in transit,’ she observed, gazing at one of the columns.

‘How do you mean?’

‘On its way to becoming something else.’

He nodded thoughtfully. ‘Yeah. I guess. Polymorphous. Going through different stages.’

As he spoke, she couldn’t get the image of the suffering, despairing slaves out of her head. The columns, fluted and massive, were stone, not coral, and they must have had quartz or something in them since they glittered in a way she found malicious. Slavery seemed such a vast and forbidding area of human experience to consider that she was almost glad when an African businessman, wearing a suit and clutching a purple briefcase to his chest, rushed between her and the awful columns.

‘They don’t seem kind of, so poor here as on the mainland,’ she said, watching the man dash away.

‘Tourists,’ said Nick. ‘There’s more money coming in here now than ever. It’s the mainstay of the economy since the price of cloves went down.’

‘Why did it drop?’

‘I’m not sure. I’ll have to ask Leggatt. He’s a clove farmer. I think people used to smoke clove-flavoured cigarettes in the Far East and now they don’t.’

They remounted. He took her down Creek Road, past lines of fishermen carrying nets on their backs, to a place that really was a museum. Its exhibits included snakes in jars, Dr Livingstone’s medicine chest, and a skeleton said to be the bones of a dodo. They looked more like those of a large hound.

They spent some time looking at carved doors on a street of Arab houses. Larger, darker and more ornate than the ones on the Indian shops, which Miranda suspected must have been modern imitations, these doors were covered with black metal roundels and spikes. In between, curled lines of calligraphy were etched into the wood like some kind of code. The carving was very elaborate. It was hard to pull one’s eyes away from it, and the doors seemed to speak not only of all the labour absorbed in their making, but also of all the hours others might have spent looking at them. The geometric motifs themselves, she realised at once, expressed the logic and order of the Islamic world view: it was as if the repeating patterns and endless divisions were trying to represent God’s unchanging laws.

They got back on the bike and drove around a bit more. For all Nick’s efforts, Miranda still wasn’t that impressed by Stone Town. There was a sweltering, squalid quality to the place, and there were mosquitoes everywhere. The town didn’t conform to how she had imagined Zanzibar, which was, well – long white beach, spread of palms at the water’s edge, etc. Her mood wasn’t improved by a waiter in the restaurant they went to for dinner sneezing as he brought their food, nor by Nick’s awkward attempts to flatter her.

After eating, they went dancing at Spices Nite-Club. The live music – twangling, Afro-style guitars – cheered her up. As they whirled around together, the awkwardness lessened. She realised, as the music hummed about her ears, that she hadn’t danced since coming to Africa. At one point, when the music was appropriate, he held her hips. It excited her, she wanted to feel his hard chest’s weight on her – and it made her wonder, too, whether he just hoped for sex, or thought more of her.

They sat down and talked a little. In spite of the compliments, which kept coming, it was still quite hard to sense whether he was hopeful of anything serious developing. It was strange how men could be so closed off like that, voice and eyes ever alert to the betrayal of emotion. It was as if they were addicted to secrecy. Of course, women concealed their feelings too – it was a necessary part of life – but men seemed to do it as a matter of course, as if to open up at all made them entirely vulnerable.

By the time they arrived at the Macpherson – he’d booked a room for her there – the lights had gone out. They had to make their way to her chalet, guided only by Nick’s cigarette lighter and the moon and stars coming down into the courtyard between the chalets, reflecting up off the pink coral gravel.

He sprung a tentative kiss on her cheek as they said goodnight on the step. Again, it was hard to read, in itself as much as in the semi-darkness. She could see his eyes well enough in the flame, and they were surely expectant.

Her wondering – that glorious uncertainty which affects all those whose hearts are stirring – took too long. His shoulder had already begun to turn as he made to go down the steps. She said goodnight a second time – he turned again, said goodnight once more himself – and then she went inside, shutting the door, perhaps a little slowly, perhaps a little slyly, behind her.

Moonlight, and a hushed sound of waves, filled the room. She went over to the French windows and stood for a moment, looking at the silvered sea: a mixture of pearl, soot and polished metal. The sky near the moon was illuminated by a skirt of clear, grey calmness; the rest was a deep, impenetrable black, utter but for the pinpoints of stars, which shone much more brightly than at home.

She thought of her father, her mind settling on the blue felt policeman’s cap he kept as a memento after leaving the job and which she still had. She had put the cap into storage for safe keeping when she came to Africa. Its main feature was the badge: ‘BOSTON POLICE’, silver letters on a blue background. There was a tiny emblem of Paul Revere on his horse between the words, commemorating his ride to warn the revolutionaries that the British were coming. Beneath ‘POLICE’ was the civic crest, a depiction of the city skyline from the harbour with three boats. Under that were the words Bostonia Condita AD 1630.

Her mother, who died when she was just three years old, might just as well have come from such a distant period of history. Everything about her was hazy. Whatever memory of a happy family Miranda retained came through her father. She remembered the smell of the cap and the cap remembered his smell: fried bacon, oil and exhaust, soap, tobacco, beer.

He was a good man. Apart from when he’d drunk too much, which was only very occasionally, he was sweet and kind, a slight frown sufficing for his anger. Recalling talking about him with Nick back on the beach in Dar, she wondered if that was what had drawn them together. He had, in a way, something similar.

She began to undress, feeling strange, divorced from herself, excited still but a little solemn also, happy, yet oddly forlorn. Nevertheless, it was nice to go to sleep with the noise of the ocean in her ears.

In the morning, she met da Souza at breakfast, after which Nick took her down to the beach, to show her his dinghy and a mangrove stream and some places where turtle eggs had been. After that she once again hitched up her skirt over the back of his motorbike.

They drove to somewhere called Jozani Forest, which was shadowy and slightly frightening. Monkeys rattled the trees; the blooms of the flowers, purple and deep blue, oozed with mysterious secretions. On one tree at the edge of the forest, four or five large birds, a little like peacocks, were perched side by side; their long, spangled tails gave the impression of a light curtain or veil where they hung down from the branch, with the sun shining through and indistinct green hills beyond.

For lunch they rode across to another little hotel on the west of the island, run by two gay Germans. It was a lovely place, at last delivering what she had hoped for. Something exalted happened to the acoustics on the beach, which ran at least ten miles either side of the hotel. The reef surf seemed to place its distant roar behind you as well as – out there, where you could see its proud-standing, always-moving line of white – in front.

‘Surround sound,’ said Nick, and suddenly she felt pleased that she was with him rather than with Ray.

She took off her sandals so that she could feel the sand between her toes and ran down to where an outrigger canoe was washing to and fro in the surf, tugging at its coconut-fibre mooring.

‘I wouldn’t want to go to sea in one of these,’ she said, when Nick caught up with her.

‘They’re pretty stable actually. But don’t worry, I’ll take you out in my boat tomorrow. You can spend your last day on my island.’

‘Your island?’

‘Not really,’ he laughed. ‘Just somewhere I go to work. Well, to chill out really. It’s called Lyly. Spelt L-Y, L-Y.’

‘How far is it?’

‘You worried?’

‘It’s not a very big boat.’

‘We could go in the British guy’s yacht, if he’d take us. You more comfortable with that idea?’

‘A yacht? Sure.’

‘We’ll go and ask him tomorrow.’

They walked, mainly in silence, up the beach for a while – to where some women, squatting down, were harvesting seaweed into deep baskets. They watched for a while before turning round and heading back.

After eating lobster salad at the German place, they returned to the Macpherson, by which time it was almost evening. Kicking out the stand, Nick parked the motorbike under a tamarind. The sun was coming down through the big tree’s branches, throwing leopard-skin shadows on the sand round the larger patch cast by the leaning motorbike.

Nick said, ‘Do you want to go for a walk in the gardens? They’ve got all the species. The local plants, I mean.’

‘OK,’ she responded, evenly, and they walked over to the garden under the deep red sun.

Soon they were moving along the paths between the trees and shrubs and flowers. Between philippine violets and wild custard apples and, so the label said, though it was hard to read in the fading light, hop-headed barleria. She felt drowsy as she walked beside him, which was probably, she reasoned idly, all the oxygen from riding on the back of the motorbike. But it could have been the smells of the plants which were making her feel so sleepy and warm – the tropical blue sage, or the cinnamon, or the star jasmine…

Or may it have been, as their hands brushed, that the air was simply thick with possibility, heavy with prepared likelihood that he would turn and, bolder now, kiss her beside the flower of love or the rub-rub berry?

But he didn’t. He kissed her beside the false globe amaranth. All those other names that might have been germane – on the one side the hare’s foot fern, the fire bush, the convolvulus, the purple grenadilla and the java plum; on the other, the flowering banana, the ashok mast tree, the snake plant and the silver quill – all those other names were beside the point. They’d lifted clear of earth, it seemed, for a brief passage were beyond the Macpherson gardens and the deep red sun suffusing them, beyond, even, their own mouths as they met.

This wasn’t supposed to happen, she thought, as he kissed her. How on God’s sweet earth, she sweated, had she let it? How had she been brought into the arms of a man she hardly knew, on an island on the edge of the world? She realised she could hear water in the glade someplace, the sound of a stream in an upland part of the garden, rolling down towards them over twisted roots. They kissed some more. The sun’s rim dipped.

It was almost dark by the time – brows and armpits prickling in the intense heat, lips and earlobes full of bee-stung lovers’ blood – they made their way back to the hotel building. She was rationalising now, thinking that it hadn’t been so sudden since there’d been so much anticipation. The emails were just part of a deeper seam of inchoate, half-willed plans which had been laid down long before. It had begun weeks ago, at the embassy, the moment their eyes had met. Watching over them, back then, the security camera on the chancery wall could not have picked it up – but something had happened, a change had taken place, the needle had swung round in the compass of the heart.