A discreet advertisement in ''The Times'', addressed to ''Those who Apppreciate Wisteria and Sunshine...'' is the impetus for a revelatory month for four very different women. High above the bay on the Italian Riviera stands San Salvatore, a mediaeval castle. Beckoned to this haven are Mrs. Wilkins, Mrs Arbuthnot, Mrs Fisher and Lady Caroline Dester, each quietly craving a respite. Lulled by the Mediterranean spirit, they gradually shed their skins and discover a harmony each of them has longed for but never known.First published in 1922 and reminscient of ''Elizabeth and her German Garden'', this delightful novel is imbued with the descriptive power and light-hearted irreverence for which Elizabeth von Arnin is renowned.