Caillou thinks hes seen a flying saucer in his yard just like the one in his comic books and hes determined to prove it to his preschool class! Trying to catch a flying saucer is much harder than he thought, and Caillou is disappointed when he eventually discovers his flying saucer is only a tin plate blowing around in the wind. Now what will he tell his friends? Caillou feels much better when he realizes he solved the mystery, regardless of what the flying saucer turned out to be.