The Jewel Robbery at the Grand Metropolitan (S05E08)

Under orders from his doctor, Poirot is taking a holiday in Brighton on the south coast of England. His arrival coincides with the opening of a new production of 'Pearls Before Swine'. Leading lady Margaret Opalson wears a magnificent pearl necklace for her stage role which once belonged to the Russian royal family. When the necklace is stolen, Poirot feels obliged to break his holiday and recover the gem. (iTunes)