It reads like Hollywood's latest blockbuster:
Explorers from Tampa-based Odyssey Marine Explorations Inc. retrieve 17 tons of gold and silver from the bottom of the Atlantic Ocean. Spain immediately claims the treasure as its own, prompting a years-long, high-stakes legal fight.
The U.S. government secretly intervenes, offering to support Spain's claim to the treasure in exchange for a multimillion dollar painting that had been stolen by the Nazis from a Jewish family that now lives in California.
The U.S. State Department's role in this real-life drama came to light Thursday in the latest release of Wikileaks documents.
Odyssey officials, outraged that their own government would attempt to undermine their claim, question just how much damage the State Department has done to their efforts to hold onto the $500 million trove.
"Since the U.S. State Department first became involved in the 'Black Swan' case, we've questioned its motives, especially given that its view of sovereign immunity is contrary to the position always advanced by the U.S. government prior to this case," Melinda MacConnel, Odyssey vice president and general counsel, said in a statement.
"We will certainly be interested to follow up with this new evidence and determine its relevance to the case and the appeal," MacConnel said.
The State Department's proposal to Spain was discovered among the 250,000 classified cables recently published by WikiLeaks against the will of the U.S. government.
The State Department declined to comment Thursday.
"We cannot speak to the specifics of any document . . . illegally obtained from the U.S. government," said Nicole Thompson, a spokeswoman for the State Department.
England's Guardian newspaper, which was one of a handful of news organizations to receive the cables directly from WikiLeaks, first reported the offer from the U.S. government to Spain on Thursday.
The cables linked the U.S. and Spanish interests in both the treasure, given the code name "Black Swan" by Odyssey officials, and the French impressionist painting, Rue Saint-Honore, Apres Midi, Effet de Pluie, by Camille Pissarro.
The painting, a picture of a rain-soaked Paris boulevard now valued at $20 million, belonged to a wealthy German Jew, Lilly Cassirer Neubauer. Her husband bought it from the artist in 1897.
In 1939, as the Nazis increasingly threatened the Jews, Cassirer "was forced to relinquish the painting to an official appraiser of the Nazi regime official to obtain exit visas out of Nazi Germany," court records show. Cassirer was later given some restitution, but the painting is what the family wants.
Though it changed hands several times over the course of almost six decades, the Cassirer family eventually found that the painting had become part of the collection at the Thyssen-Bornemisza Museum in Madrid. The Spanish government bought the painting as part of a $327 million collection of works from a Swiss art collector, Baron Hans Heinrich Thyssen-Bornemisza.
Unable to convince the Spanish government that the Cassirer family was the rightful owner of the painting, Claude Cassirer, Lilly's grandson, in 2005 filed suit against the Kingdom of Spain and the Thyssen-Bornemisza Collection Foundation.
Two years later, the Odyssey explorers found the "Black Swan" treasure that was part of the 1804 shipwreck of the Nuestra Senora de las Mercedes. The warship was en route from South America to Spain when the British sank it off Portugal.
In December 2009, a federal judge in Atlanta awarded Spain claim to the treasure. But Odyssey has appealed that ruling and has a hearing in late February.
In the cables published by WikiLeaks, the U.S. ambassador in Madrid, Eduardo Aguirre, noted in July 2008 "that while the Odyssey and Cassirer claim were on separate legal tracks, it was in both governments' interest to avail themselves of whatever margin for maneuver they had, consistent with their legal obligations, to resolve both matters in a way that favored the bilateral relationship."
Such negotiations are not unusual, says Winston Nagan, director of the Institute of Human Rights & Peace Development, and a research scholar at the University of Florida.
But WikiLeaks' publishing of the cables aired the usual diplomatic actions in public. "They don't usually see all of that," Nagan said. "This is where diplomacy and discretion are valuable.
"Quite often the reason you're going diplomatically is because the legal issues may be very complicated," he said. "It's an interplay of politics and all kinds of weird stuff. . . . 'Why can't we forget all the conflict and see if we can make a deal?' "
Greg Stemm, Odyssey's chief executive officer, said he won't make any final conclusions about the State Department's offer to Spain until he hears directly from the State Department. But he voiced dismay.
"The cables seem to indicate that someone in the U.S. State Department has literally offered to sacrifice Odyssey and its thousands of shareholders along with the many jobs created by the company in exchange for the return of one painting to one U.S. citizen. It is hard to believe that this really happened."
Times researcher Caryn Baird contributed to this report.