Pearls Mean Tears

Bertie is called to Westcombe-on-Sea by Aunt Agatha, delaying a vacation in the south of France.  There he meets a girl by the name of Aline Hemmingway whom she wishes him to marry.  She and her brother leave pearls as security for a hundred pound loan from Bertie. But when both the Hemmingways' pearls and Aunt Agatha's pearls disappear, trouble arises.
Meanwhile, Bertie runs into Biffy Biffen, who has lost his fiancé in the most remarkable manner.  Unfortunately, he is unable to remember her last name - in fact he is unable to remember almost anything.