Zero Hour is Ray Bradbury's 1947 - included in Bradbury's collection of short stories entitled The Illustrated Man, released in 1951 - short story following Mrs. Morris and her daughter, Mink. Mrs. Morris is incredibly amused by how excited Mink is for a brand-new game called Invasion. Some chit-chat between the adults happen, and the kids play more Invasion. Nevertheless, after Mrs. Morris learns more about the alien invaders, their mission - the aliens couldn't figure out how to invade Earth so they use the imagination of kids, who are promised a world where they can do whatever they want - and their head honcho, Drill. Things boil over when Mink and friends get scared because they fear Drill and the aliens are coming to invade the Earth. Finally, the aliens arrive as explosions rock Mink's home.
Although Zero Hour is not widely known (nor considered one of Bradbury's best works), it represents a solid entry in his extensive bibliography. It is certainly an interesting story, though not one that will be remembered as another one of Bradbury's science fiction classics. For context, on book review aggregation site Goodreads.com, Zero Hour holds a respectable rating of 3.85 out of 5 stars.
Zero Hour was later adapted into a less well-received incarnation of the TV Show "The Ray Bradbury Theatre." Released in 1992, the episode "Zero Hour" holds a slightly below average review of 6.6 stars out of 10 on movie and TV show megasite IMDB.com.