40 years ago, a worn-out white Gulfstream II jet descended over Fort Lauderdale, Fla., carrying a regal but sickly passenger almost no one was expecting. Aboard were a Republican political operative, a retinue of Iranian military officers ... and Mohammed Reza Pahlavi, the newly deposed shah of Iran. The only one waiting to receive the deposed monarch was a senior executive of Chase Manhattan Bank, which had not only lobbied the White House to admit the former shah but had arranged visas for his entourage. Less than two weeks later, on Nov. 4, 1979, vowing revenge for the admission of the shah to the United States, revolutionary Iranian students seized the American Embassy in Tehran and then held more than 50 Americans - and Washington - hostage for 444 days. The shah, Washington's closest ally in the Persian Gulf, had fled Tehran in January 1979. The shah sought refuge in America. But President Jimmy Carter ... refused him entry for the first 10 months of his exile. Chase Manhattan Bank and its well-connected chairman worked behind the scenes to persuade the Carter administration to admit the shah, one of the bank's most profitable clients. For Mr. Carter, for the United States and for the Middle East it was an incendiary decision. The ensuing hostage crisis enabled Ayatollah Ruhollah Khomeini to consolidate his theocratic rule, started a four-decade conflict between Washington and Tehran ... and helped Ronald Reagan take the White House.