Cat’s family has just moved to Bahía de la Luna, leaving behind their life in southern California. Cat is sad to be separated from her friends, but the coastal weather will be better for her sister’s health. Maya has cystic fibrosis, and the cool seaside air may help her struggling lungs. Bahía de la Luna turns out to be haunted, and the residents of the town take living alongside ghosts for granted. This terrifies Cat, but Maya is determined to meet a ghost for herself. Unfortunately for Cat, their new neighbour Carlos knows all the best spots as the local tour guide, including the abandoned mission. In order to help her sister, Cat will have to face up to her own fears.