The night of the triffids - Simon Clark

At the end of THE DAY OF THE TRIFFIDS, the hero, Bill Masen, his wife and four-year-old son leave the British mainland to join a new colony on the Isle of Wight. This tiny community, temporarily safe in its island fortress, begins its work not only to eradicate the triffid menace but also to lay the foundations for a new civilization. THE NIGHT OF THE TRIFFIDS takes up the story twenty-five years later. David Masen, the now grown-up son of Bill, is a pilot, still searching for a method of destroying the implacable triffid plant as it continues its worldwide march, seemingly intent on wiping out humankind. David eventually manages to reach New York, where a very different sort of colony has been set up, a colony whose members seem to be immune to the triffid string and where David comes face to face with an old enemy from his father's past.