A silver flask, curved to fit a hip pocket and large enough for a good hangover, sits in a glass case in the National Portrait Gallery. It was the property of F. Scott Fitzgerald, and it has been placed next to a copy of the February 1936 Esquire, opened to the beginning of "The Crack-Up."

That's the end of the story told by the NPG's new exhibition: "Zelda and Scott: The Beatiful and Damned," which opens today. Its magic-tinged beginning is summed up in a quote from Gilbert Seldes, remembering his first meeting with the radiant young couple in 1922: "The two most beautiful people in the world were floating toward me, smiling . . . I thought to myself, 'If there is anything I can do to keep them beautiful . . . I will do it.'"

It couldn't be done. Fitzgerald, who began his career with a best seller ("This Side of Paradise") when he was only 23, was defeated finally by a frenzied social life that drained both his finances and his creative energy, by a loss of confidence in his own ability, by the need to write films and magazine pieces for money rather than novels for posterity, and finally by a drinking problem that was both symptom and cause of his decline.

That story is told here in photos, drawings, portraits and souvenirs, letters and telegrams, the silver flask and an enormous blue-green feather fan that Zelda bought with some of Scott's early royalties. It is told most graphically, perhaps, in two telegrams Fitzgerald sent to his agent near the beginning and the end of his career. The first, dated March 6, 1922, has a careless flippancy: "Awful mess in check book. Can you deposit four hundred more immediately?" The second, dated June 13, 1939, is tinged with despair: "My commercial value can't have sunk from 60 thousand to nothing . . . Can't you arrange a few hundred advance from a magazine so I can eat today and tommorrow?"

About one-quarter of the approximately 80 pieces are from the NPG's permanent collection. Staff members of the Gallery have been assembling the remainder since last October, from old friends of the Fitzgeralds, other museums and university libraries, and the Fitzgeralds' daughter, Scottie Fitzgerald Smith. The exhibit has paintings by Zelda, including her design for a cover for "The Beautiful and the Damned" -- a nude woman reveling in an enormous cocktal glass.

Editorial genius Maxwell Perkins nursed "This Side of Paradise" into print through agonizing revisions and later performed similar services for Hemingway and Wolfe. One key item in the exhibit is the handwriting original of the 1924 letter in which Fitzgerald first told Perkins about Hemingway: "This is to tell you about a young man named Earnest Hemmingway [sic], who lives in Paris (an American) writes for the Transatlantic Review and has a brilliant future . . . He's the real thing."

When Fitzgerald wrote that, everyone seemed to have a brilliant future. The exhibit's dramatic demonstration that this was not true will be on display through Dec. 1.