DEATH stole over the countryside that morning in ways that were decidedly unreal.

A too-extravagant sky. A herd of bullocks, each with a thin channel of blood trickling from its ear. A flock of grouse, unable to fly. Such signs make the small cluster of men - among them, Artyom, a boy of 13 - uneasy. They have no possible explanation for them.

It is April 1986. Ten miles away from these men, in Belarus, lies a nuclear power plant, the name of which would shortly become infamous as the location of the world's worst nuclear disaster. Chernobyl forms the backdrop to Darragh McKeon's exceptional debut novel and, just as the disaster's environmental consequences are still being felt in real life, so too does its shadow hang over his characters right up to April 2011, when the action ends.

Grigory is chief of surgery at a Moscow hospital, newly turned 36. Through a injury inflicted on Yevgeni, a nine-year-old piano-playing prodigy, Grigory is re-acquainted with his former wife, Maria, the boy's aunt. Maria lives in an apartment with her widowed sister, Alina, Yevgeni's mother, who makes a living by doing other peoples' laundry. She and Maria have high hopes for the boy - who, however, is obliged to practise in silence for fear of annoying his neighbours. The other main character is Artyom, the rural youngster whom we first encounter on the morning after the disaster, when he wakes to that unreal sky of the deepest crimson.

Once news of the disaster is confirmed, Grigory is asked by Vygovskiy, chief adviser to the Ministry Of Fuel And Energy, to take charge of the medical operations. He is stunned by the presence of a radioactive cloud over the city of Minsk, by the authorities' blind refusal to alert the population. His conscience does not allow him to stay quiet.

When Grigory had his first meaningful encounter with Maria, he was a junior hospital registrar in Kursk, she a hospital cleaner. What later emerges, however, is that Maria, who had once been a free-spirited, independent-minded student, later became an inquisitive and rather good journalist whose career was threatened by the discovery of some underground articles she had written.

"What followed," writes McKeon, "was a dangerous time for her. She had to realign all aspects of her personality; was forced to erase her outspoken nature; every word she spoke from that moment would be sifted through and interpreted."

This speaks to the relentlessly grim and secretive way of life in the Soviet Union, even in the early days of Gorbachev's radical domestic reforms, when the Communist system was starting to crumble. You never knew who you could trust, you had to watch what you were saying. It had always been this way.

Maria and Alani have known this since they were very young. Their own father had his own dubious, damaging secret life: "The father," writes McKeon, "went to the races on a Saturday afternoon and never returned. There were no explanations or justifications for his work; how he betrayed others, led them to a life of imaginable misery."

Reading All That Is Solid Melts Into Air (the phrase comes from Marx's Communist Manifesto), you are also reminded of the extent to which the authorities thought Chernobyl would never happen.

Just as Reactor No 4 exploded and went on fire, McKeon has dazed operators in the control room trying desperately to consult an operating manual. The section dealing with procedures in the event of reactor meltdown has been redacted in their entirety. There is nothing to help them here.

"An event such as this cannot be tolerated, cannot be conceived," he writes. "The system will not fail, the system cannot fail, the system is the glorious motherland." At this, you recall in April 1986 the real-life Soviet authorities downplaying the incident, imposing a three-day virtual news blackout, describing it not as a catastrophe but as an accident.

It is this subtle blending of historical reality with the vividly-sketched lives of fictional people who are, one way or another, caught up in the fall-out from Chernobyl that gives All That Is Solid... its power. The story unfolds at its own unhurried, reflective pace, and you find yourself interested in the fates awaiting Grigory and Maria.

Grigory's own story is, in particular, handled with acute skill and empathy. This is an affecting, compassionate, thought-provoking, strikingly well-written novel.