The weather has become extreme, threatening the whole of continental Europe and turning the lives of its citizens inside out. The French government calls Professsor Mortimer to help solve the enigma. Mortimer travels to Paris to visit his friend, Professor Labrousse, the French chief meteorologist - but when the taxi driver sent to meet him at the station disappears, Mortimer becomes the prime suspect. Mortimer gets in touch with his old friend, Blake, who also happens to be in France, to help him out of this tricky situation...