The Jewel of the Nile (1985)

After six long months of dreamlike sunsets, seductive cocktails, and endless travels around the globe on their yacht, Jack Colton and Joan Wilder are finally starting to get bored with their stagnant relationship and the easy life. However, life will soon get back in the fast lane, when a polite but insistent invitation by the sinister aspiring monarch, Omar, involves Joan in a new adventure in the Nile and the deserts of Anatolia, hot on the trail of yet another mythical gemstone. Is this elusive "Jewel of the Nile" the missing ingredient in Jack and Joan's love life?