While on a trip to a movie studio, Tommy, Chuckie, Phil, Lil, Angelica, Susie, and Dil venture away from the grownups. But in the process, Dil gets locked behind a door, and the security guard loses the keys to the door thanks to Dil himself. It's up to the babies to find all the keys to that particular door and get Dil back! Source: Wikipedia, "Rugrats: Studio Tour", available under the CC-BY-SA License.