Since "Zero Hour" and "Mushrooms" are both primarily suspense stories, they share a number of structural traits common to such stories. For instance, the secret of the invasion is revealed to the reader almost at once. Real-life invasions usually depend heavily upon the element of surprise—such as in the attack on Pearl Harbor or in the invasion of Normandy. But in a story it is difficult to sustain reader interest if the main point is concealed until the very end. By revealing the invaders' intentions at the beginning of the story, Bradbury keeps us in constant suspense, wondering if and when the protagonists will catch on. In both stories, the method of invasion is rather improbable. This is necessary because the main character must be teasingly slow in putting the pieces of the puzzle together—but without coming off as an idiot. Because the invaders' plans are...