John Christopher's mid-1950s vision of worldwide eco-disaster was recently named among the top 10 out-of-print books in Britain. It has now been reissued as a modern classic, and it's hard to understand why it has been ignored for so long. A virus that attacks all species of grass, including wheat and rice, has caused mass starvation in China and is heading this way. John Custance and his family flee London, though the journey becomes increasingly treacherous due to the rapid breakdown of civil and moral law. You could argue it is too convenient that the hero has a friend in the Ministry of the Environment with access to classified information, as well as a family farm to escape to in Cumbria. The prospect of atomic bombs being dropped to reduce the population may also have seemed more imminent in 1956 than it does now. But the swiftness with which society reverts to savagery is remarkable, and the evocation of man's culpability for the disaster - "For years now we've treated the land like a piggy bank, to be raided" - could hardly be more prescient.

"As sometimes happens, death healed a family breach." The opening sentence of John Christopher's 1956 novel would be benign were it not for that cautionary "family". Death may have healed a personal divide but might yet open a general chasm, which is precisely what occurs in The Death of Grass when a virus destroys the world's food supplies and the flimsy edifice of civilisation itself.

At first, only incompetent Asiatics are affected by the lack of rice; "the British peoples", huffs the Daily Telegraph, must once again "set an example to the world". This hubristic raspberry is duly followed by the grass plague's arrival in Blighty, where the powers-that-be are soon as helpless as the general public. With sufficient food reserves for only half the population, the government takes the radical decision to bomb major cities.

Against this backdrop two families make a bid for freedom by escaping to an isolated Cumbrian farm. PR man Roger Buckley is the group's natural leader but it is engineer John Custance who assumes the role of shepherding "his" people through the terrifying "them" that his countrymen have become. The veneer of politesse is quickly shattered - once the meat and potatoes run out, the well-mannered Anglo-Saxons turn into a raping, murdering mob. By the end of the book, identity as well as territory belongs to those with guns.

As Robert Macfarlane observes in his introduction, despite the sci-fi title, Christopher's book has more in common with the Lord of the Flies than The Day of the Triffids. Not quite a masterpiece of prophetic eco-menace , but a riveting, brutal human drama nonetheless.