In Sensors, Olive and her cousin, Troy, help their family remodel a quaint old lodge in the mountains. They decide that the old building could use some modernization. A visiting inventor suggests some sensors that would help. Sensors are devices that respond to heat, light, sound, pressure, magnetism or motion. The inventor explains the principles behind different types of sensors that can detect the presence of something, such as smoke detectors, automatic doors and security alarms.