After a bomb destroys a railway carriage, the four survivors repair to the villa of one, Mrs. Delahunty, a writer of romance novels, a woman with a past. The others are an aging British general, a young German man, and Aimee, an American girl orphaned in the blast. As these four strangers recover in Umbria's countryside and become friends, Aimee's uncle, a cold and childless academic who studies red carpenter ants, arrives to fetch her. Mrs. Delahunty fears this may not be in Aimee's best interests, begins to drink heavily, and fails in her attempts to connect with Aimee's uncle. Meanwhile, a persistent detective investigates the blast.