The blurb tells us that the story begins in 1899 in a coastal village near Mombasa in what was then called the East Africa Protectorate and would later be called Kenya, and that it is about a passionate love affair between Martin Pearce, an Englishman, and Rahana, a Muslim girl, but we have to wait until page 108 before that starts. By then the novel has established several characters: three Englishmen - Pearce; a District Officer called Frederick Turner; and a coarse estate manager called Burton - and Rahana's family - her brother Hassanali and her sister-in-law Malika. It has also brought to life the local scene, with its African, Arab and Indian population and the customs of the villagers. The plot so far has been on the thin side; but we have learnt the history of the area and the attitude of the British towards the local people mainly from several didactic passages in the dialogue between the Englishmen.
A mere twelve pages after the love affair has started, it has reached its conclusion, and so has Part I. In Part II we are suddenly brought into an apparently unrelated story, with a different set of characters, this time set in Zanzibar a little over 50 years after the earlier story. These new characters - two brothers, their sister, and their parents - and their relationship to each other are well described (that between the brothers is particularly touching), but again there isn't much of a plot. The older brother, Amin, is in love with a girl - and like the love affair in Part I, this one runs in the face of disapproval - in the first part on account of race, in the second part at least on account of the girl's background and uncertain reputation.
Part III is written twenty years later, in the 1980s. The younger brother, Rashid, had won a scholarship to study in London, and he recounts the unfriendliness and the racism he found there (this is 1963). Soon after his arrival Zanzibar had became independent, and within a few months of independence there had been a bloody revolution on the island when the African majority there turned against the ruling Arab minority. Rashid's father had told him not to return home, so Rashid now also saw himself as an exile. He made a career for himself at an English university. This all seems very autobiographical). His correspondence with his family becomes more artificial. We now understand for the first time the title of the book. But there is another desertion we will learn about.
And suddenly, in what seems a throw-away line, we find that the stories of Part I and Part II have a link, (though perhaps we might have guessed what it was); we understand why there seemed to be such a break between it and the later parts; and the story that was broken off so abruptly at the end of Part I is now resumed.
Unlike another reader, I found this third part much the best - perhaps because it describes Rashid's (i.e. the author's) feelings instead of the feelings of all the other characters in the book, which, by comparison, are seen more from the outside and perhaps not quite as deeply experienced. And you cannot say of Part III that there is hardly any plot! My estimation of the book went up a great deal.