When her father dies, Epifania Parerga, an Italian in London, becomes the world's richest woman. She feels incomplete without a husband and falls in love with a humble, Indian physician, Ahmed el Kabir, much loved by his indigent English patients.

A wealthy businessman schemes to steal the valuable Crown Jewels from the heavily guarded Tower of London, but many tricky factors await, including a doppelgänger and a vessel escape on the Thames.