The Secret Kingdom (1998)

You never know what you'll find under the kitchen sink. When a curious little kid accidentally discovers a magnificent miniature city nestled behind the kitchen sink, his teenage brother and sister, two terrified teens, are soon transported into this strange land where people are surgically altered to suit their jobs and two powerful kingdoms from another time and place are about to go to war. It is up to the kids to restore peace among the people... and to save their own lives.