Covered in dirt and sweat from playing an exciting game with the other neighborhood kids, seven-year-old Mink Morris runs into her house in search of supplies. As she crams pots and pans into a sack, her mother, Mrs. Morris, asks what’s going on. Mink explains that she needs the kitchen supplies for a new game called “Invasion.” Mink runs back outside, slamming the door behind her.
Mrs. Morris peers out the window and watches Mink playing below. Mink is talking animatedly to a rosebush, but no one is there, which Mrs. Morris thinks is odd. When Mink comes in for lunch, she gulps her milk down quickly and tries to run back out to play, but Mrs. Morris forces her to sit and wait for the soup to be done. While she waits impatiently, Mink talks to her mother about a boy named Drill. Mrs. Morris asks if he’s a new boy in the neighborhood, but Mink is evasive and fends off her mother’s questions by claiming that she’ll “make fun” of Drill just like “everybody” does. Mrs. Morris asks about the Invasion game, and Mink explains that Martians—who are “not exactly Martians,” as she’s not sure what planet they’re from—are invading the Earth.
Mrs. Morris tries not to laugh, and Mink continues, explaining that the aliens had a hard time figuring out how to attack Earth, and it wasn’t until recently that they came up with a plan. She says that, according to Drill, the aliens needed the element of surprise and help from the enemy but couldn’t figure out how to do so. Recently, however, the aliens realized they could use children to help them from within. Mink says the plan is a good one because “grownups are so busy they never look under rosebushes or lawns.” Bored of Mink’s chatter, Mrs. Morris sends her daughter back outside but reminds her to be back in time for her bath. Mink declares that after the Invasion, kids won’t have to take baths anymore. According to Drill, kids will get to watch more television, go to bed later, and even rule the world—and even better, Drill promised that Mink will be queen.
Mink tells her mother that she hates the older kids in the neighborhood, like Pete Britz and Dale Jerrick, because they refuse to believe in Drill and just make fun of the younger kids. She also tells her mother that parents don’t believe in Martians, which means parents are dangerous. Mink pauses and asks her mother about two words Drill used earlier that day, which she didn’t understand: “lodge-ick” and “im-pres-sion-able.” Mrs. Morris explains that logic is knowing what’s true and false, while impressionable means “be[ing] a child.” Mink thanks her mother and tells her that she “won’t be hurt much” in the Invasion. She runs back outside to play.
Mrs. Morris talks on the video phone with her friend Helen, and the two women are surprised to realize that their kids are playing the same Invasion game, even though they live in different parts of the United States. The women reminisce on the games they used to play as children back in 1948 (including one called “Japs and Nazis”) and affirm that “parents learn to shut their ears” to children’s distracting chatter and silly games. Mink runs in for a glass of water but runs right back outside, yelling that “zero hour” is at 5:00 P.M., so she needs to hurry.
When Mr. Morris gets home from work at 5:00 P.M., he greets his wife warmly. Suddenly, a strange buzzing noise engulfs the neighborhood and gets increasingly louder. Mrs. Morris nervously asks her husband to tell the kids to put off their Invasion game until the following day. Before he can do so, an explosion shakes the house. Mrs. Morris screams and drags her husband upstairs to the attic. She locks the door behind them and tosses the key across the room, “babbling wild stuff” as she does so. Mr. Morris thinks his wife has gone crazy, but she is overcome by all the little realizations and suspicions about the Invasion being real that she had logically ignored all day.
Below them, Mr. and Mrs. Morris hear their house fill with the sound of footsteps, belonging to at least fifty people. Mr. Morris shouts about trespassers in his house, but Mrs. Morris begs him to be quiet. The footsteps get louder, accompanied by Mink’s voice, calling out for her parents. Suddenly, the lock melts, and the attic door swings open. Surrounded by “tall blue shadows,” Mink says, “Peekaboo.”