In the heart of a bustling city, a simple errand becomes the adventure of a lifetime for two young siblings in this charming family film. When they are accidentally left behind at their father's high-tech office building overnight, the brother and sister find the empty skyscraper transformed into a vast, mysterious playground. Led by Victor Ertmanis and featuring a supporting cast including Gale Garnett and Barbara Gordon, the film follows the resourceful kids as they navigate darkened corridors and automated systems, turning everyday office equipment into tools for exploration and survival. Their whimsical journey is peppered with lighthearted challenges and unexpected encounters with nighttime staff, including a kindly janitor played by Eric Keenleyside. Directed by David Dobkin, this delightful adventure captures the thrill of childhood independence and imagination, weaving a story that proves even the most ordinary places can become extraordinary when seen through the eyes of a child.