In Antoine de Saint-Exupéry’s much-loved The Little Prince a slippery, sinister snake appears who “twined himself around the little prince’s ankle, like a golden bracelet”. That snake is moved from the margins of Saint-Exupéry’s tale to the centre of the latest book by AL Kennedy. The Little Snake is about a little girl called Mary, who lives in an unnamed town where they fly kites from the rooftops – “some looked like birds of paradise, some looked like fish and some looked like wonderful serpents”. The snake comes to visit Mary and her kindness to him forges a lifelong bond between the two, eventually causing the snake’s lifeless heart to start beating.

The snake reveals his name is Lanmo – Haitian for death – and we understand that usually his appearance means the end of a life. We follow him to a number of victims, some of them evil, some good, and for each he “opened his beautiful mouth and his tiny needle teeth shone white as bone”. However, he confides in Mary that humans have recently been taking death into their own hands. “It seemed strange to the snake that so many humans would use so many ingenious machines and so many ingenious excuses and so many ingenious methods to rush each other out of the world, when all of them must leave their lives in any case.”

Mary grows older, wars are fought and the city Mary lives in grows shabbier and darker. The snake attempts to help Mary escape.

We seem to be living through a bright moment in the literary life of the fable. I kept thinking of Mohsin Hamid’s hauntingly fabular Exit West as I was reading The Little Snake – it shares the anonymous cityscape, the leaps through time, the clarity of the almost childlike language; more than anything, though, it shares that book’s sense of carrying a deep moral message about modern life.

Kennedy’s slim, suggestive fable is about the need for kindness to strangers; it’s about greed and politics; it’s about migration. It’s about the lessons we learn from the books we read as kids. What The Little Snake is about more than anything, though, is the acceptance of death as an ineluctable part of life. It’s not a new message, but Kennedy conveys it here in a manner that is subtle and hugely moving.

If you know a child – or an adult – who has lost someone, give them this book.

• The Little Snake by AL Kennedy is published by Canongate (£9.99). To order a copy for £6.99 go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99