BECAUSE I WILL probably forget to mention it later on: Alif the Unseen is a rattling good yarn, full of action and adventure, revolution and romance. It is smoothly written, compassionate and generous, and has important things to say. It is the sf debut of the year.

It begins in Persia, long ago. Reza summons a supernatural being to tell him the stories contained in the Alf Yeom, also known as The Thousand and One Days, which contains “all the parallel knowledge” of the jinn. The stories seem to shift and change as they are doubly translated: first transforming from the “diffuse” and “voiceless language in which the creature spoke” into the Persian that Reza hears, and then into “mathematical and efficient” Arabic as Reza transcribes them in the scholarly language so as to keep them safe from his unlearned countrymen. Reza plans a further translation — he will give “each element of each story a number” so as to “create a code that determines their quantitative relationship to one another.” As the brief prologue closes, the jinn begins to tell the final story of the Alf Yeom, which, he warns, will make the listener someone else.

Alif the Unseen then jumps to an unnamed Gulf emirate in a very near future, not long after the Arab Spring has been pretty much neutered and channeled into the status quo ante. The half-Bedouin, half-Dravidian protagonist, Alif, is a computer hacker. He provides digital security for anyone who can afford his services: pornographers, Islamists, communists, feminists, he does not care. He is not for anything in particular; he is against censorship. And he has just been dumped by his girlfriend, Intisar, an “upper-class Old Quarter girl” whose father is marrying her off to an influential friend. Being a console cowboy, Alif responds in the only sensible way: he severs all potential avenues of communication between them by developing, although he is not entirely certain how he does it, a program that can identify, from a negligible sample and however well disguised, anything Intisar ever writes on a computer.

Which is when things start to go really badly wrong. Suddenly, Alif and his childhood friend Dina are on the run from the Hand of God, the murky head of the emirate’s security agency and the brutal enforcer of state censorship, who has repressive uses for Alif’s innovation in mind. He also has the very wrong hands into which an ancient book must not fall — an ancient book that has just been given to Alif. Which is when things begin to get generically interesting, especially for anyone expecting the kind of North-African cyberpunk adventure found in George Alec Effinger’s Marîd Audran trilogy or Jon Courtenay Grimwood’s Arabesk trilogy, or the kind of pointed but conceptually thin political allegory of Ahmed Khaled Tawfik’s Utopia. Vikram the Vampire, the gangster to whom Alif and Dina turn for help, provides a definitive turning point in the narrative because he is actually a vampire — or, at least, one of the jinn described in the Quran who, though rarely seen by humans any more, inhabit our world at an angle. This move is neither a failure of the novel’s science-fictionality, nor the kind of facile genre mash-up designed merely to indulge in romps about, say, dirigibles and zombies, Cthulhu and automata. Rather, the genre dynamics at...