On the improbable assumption that an unidentifiable and untested fungus could pass through British Customs. . . Peter and Emmelle (named for insecticide ML 17) Hendon, following their scientist-father's instructions to plant the fungus, unknowingly sow seeds of destruction. Dad returns after a brief arrest in an Asian country for (unfounded) spying, learns about the curious crumbling of buildings in the area--first Canterbury Cathedral, then up to London, finally all of southern England until the spread is checked by a barrier of pig farms (like milkmaids and smallpox). The spores are responsible for the devastation: they explode and pop into the stone of buildings, turn rock into spongy foundations, then infect trees as well. The entire family is so preoccupied with finding a solution that they never discuss the population displacement of southern England: they move to Australia after public censure and before the government scorches the earth to destroy the fungus. A startling situation, but the potential for drama is dissipated.