Wealthy, blind Agatha Kimball, who once hired Magnum to find her missing granddaughter Amy, now enlists him again after a blackmailer claims to have vital information about Amy. Agatha instructs Magnum to pay the blackmailer and suppress the information without further investigation. However, when Agatha narrowly escapes a series of suspicious accidents and the blackmailer is shot dead during the ransom delivery, Magnum disregards her orders and investigates the trouble surrounding his elderly friend and her granddaughter.