As the Triffids destroy Britain, Bill works with his father to clone a genetic mutation which will sterilise them all. Bill's future with Jo is wrenched apart with the arrival of Torrence from a London which has been overwhelmed. To escape, they will have to run the gauntlet between Torrence and the Triffids.

The world is struck blind by a solar storm, and millions of man-eating mobile plants are released to roam Britain. As an expert on the Triffids, Bill Masen knows that salvation rests in the hands of the father he hates, who mutated the Triffids in the first place to produce a green source of oil that the world craves.