At the end of The Day of the Triffids, the hero, Bill Masen, his wife and baby son join a new colony on the Isle of Wight. Temporarily safe in its island fortress, this tiny community begins its work to eradicate the triffid menace and lay the foundations of a new civilisation. Throughout the world similar colonies struggle for survival, while the implacable triffid plant continues its march, seemingly intent on wiping out humankind.

The Night of the Triffids takes up the story twenty-five years later. David Masen, the grown-up son of Bill, is a pilot who eventually manages to reach New York where a very different colony has been set up, a colony whose members seem to be immune to the triffid sting and where David comes face to face with an old enemy from his father's past...