Mohsin Hamid's Exit West is a science fiction novel with a simple, allegorical premise: what if the poor, oppressed, and alienated could simply vanish through mysterious doorways and emerge somewhere else?

Exit West opens in an unnamed city that seems to be in the Indian subcontinent somewhere (possibly Hamid's birth city of Lahore) where a young couple begin courting just as hardline militants start to conquer the city. The couple, Nadia and Saeed, have a complicated relationship to their city and its culture: Saeed is religiously observant but culturally liberal, while Nadia avoids harassment by dressing in black, severe religious robes but doesn't actually have much faith.

As the religious militants slowly take the city, Saeed and Nadia are thrown together: their workplaces shutter, their streets thrum with gunfire, the power goes, and so does the water. Saeed's mother is killed by a stray bullet and his life is shattered, and Nadia moves into the flat where he lives with his grieving father.

The city grows more dangerous by the day: the lampposts are decorated with the strung up corpses of people who transgressed against the rebels' arbitrary religious edits, and militants go from house to house, seeking out heretics to execute and valuables to loot.

But in the background, there are the growing rumors of a way out: mysterious doors are appearing everywhere, the doors of old sheds and storage closets, basements and bedrooms. These black doors open somewhere else: sometimes somewhere wealthy and peaceful, sometimes some other war-torn place. Militants slip through these doors and emerge in western cities, gunning down civilians and slipping away, and anyone in militant-occupied territory caught scheming to escape via a door is killed on the spot.

Of course, Saeed and Nadia escape through the door, finding themselves skipping across the globe, in a series of refugee camps with escapees from all the world's climate-wracked, failing places. First they're in Mikonos, then London, then the Bay Area, buying SIMs and dodging police and navitist mobs, finding friendship and watching the tense news from home with dismay as the people they love escape or don't.

The villains of Exit West are the people who want to limit the freedom of movement: militants who want to force their austere version of religious purity on people at gunpoint; states and nationalists who want to keep those fleeing war and persecution off their precious soil, and who are prepared to resort to discrimination, violence and worse.

But the doors appear, answered dreams of people desperate to leave, and it's not just refugees, but all the alienated people — a accountant on the verge of suicide in London, an old Brazilian man who falls in love with an old Dutch man when he emerges from the shed in his Amsterdam housing block. The relentless drive to change and move is pitted against the mulish insistence on things staying the same, and while the status quo has historically enjoyed the home-team advantage over the forces of change and migration, the doors tip the balance, making a mockery of borders.

It's a timely and zeitgeisty novel, a book perfectly timed for a world where the UK is willing to commit economic and cultural suicide to punish its migrants, where Australia maintains offshore rape camps to "deter" refugee claims, where Hungary has re-elected a fascist who promises to purify the country of brown-skinned migrants — where Donald Trump took office on a wave of lies about sharia law and Mexican murderers.

Moreover, it's a beautifully told tale, full of poesie and romance and sadness and delicate strands of hope. As a migrant twice over, the father of a migrant, the son of a refugee, this novel touched me.

Exit West [Mohsin Hamid/Riverhead Books]

(Thanks, Cindy!)