Brand Upon the Brain! (2007)

Guy and his sister grow up on an island. His domineering mother keeps watch over everything from the tip of a lighthouse, his eccentric father experiments in the basement laboratory. Then there are the orphans, on whose heads the adoptive parents later find puzzling wounds. Another brother and sister pair is sent to the island: the Lightball Kids, two detectives that are meant to bring light into the darkness. The brothers and sisters are all yanked into the emotional roller coaster of first love, while something cryptic comes to light in the parents' house.