The Diamond Bubble

A peculiar diamond sale pits Captain José Da Silva against his cousin

It is an ancient scam: Offer a wealthy American a massive diamond for a bargain price, have a jeweler confirm the stone is genuine, and swap it for a fake as soon as the money changes hands. At first, Captain José Da Silva assumes Senator Hastings has been taken in by an ordinary conman, but the diamond is all too real. There is a more elaborate con in progress here, and only one man in Rio would be daring enough to execute it. He is Da Silva's cousin Nestor, and he is a true genius of crime.
 
According to Nestor's scheme, the senator was supposed to sail that afternoon on the Bolivar, along with three other targets of the plot. But Senator Hastings deviated from the plan and left the boat at the last minute, which means Da Silva still has a chance to set things right—assuming he's quick enough to outwit his own flesh and blood.