A storm engulfs the island, cutting off the electricity and trapping the family, including the mumps-stricken Larry, in the house - along with the visiting aunt Hermione and her friend Mrs. Haddock, who claims to be a medium. Mrs. Haddock believes she can commune with Louisa's late husband and, against the boys' wishes, arranges a séance to see if he approves of her seeing Hugh. Larry, however, is determined to expose her as a fake and, helped by Theo, succeeds, leaving Louisa free to continue her romance with Hugh.
—don @ minifie-1