The Maserati Quattroporte, which Pietro Frua built as a prototype for the manufacturer in 1971, can be considered one of his most elegant limousine designs. Aga Khan liked the car so much that he ordered his own, which is why two vehicles with the same special body were built by hand. Both survived, and some of them were even owned by the same person. But is there a mysterious third example? This report describes the history and circumstances surrounding the construction of the Maserati Quattroporte in the early seventies and shows the two well-known cars in many pictures.