Writing is not an easy way to make a living. Even getting a book on the New York Times best sellers list is no guarantee that you will have a steady income.

That’s what Lee Israel discovered. Through her 20s and 30s she was able to make a living writing celebrity biographies. But when Este Lauder fought back against the unauthorized biography Israel was working on about her, it killed the book that resulted and sent her in to a professional tailspin. She was reduced to taking copy-editing jobs, for which she was not well suited. In fact, Israel was not terribly well suited to any job that required being in close quarters for extended periods of time with other people. Her only companion was a cat that didn’t mind her fairly lackadaisical approach to cleaning in her Manhattan apartment. (Maybe those whiskey glasses weren’t going to wash themselves, but that was their problem.)

At a low point in her life in 1991, Israel resorted to selling a personal letter she had once received from Katharine Hepburn. She learned that there was a regular market for this kind of thing, and that the prices rose if the letter had some content beyond the merely informative: a snide comment on a mutual friend, say, or a sad but witty assessment of the writer’s present state.

If Israel had in her possession a few more mundane letters, she reasoned, why not increase their value by appending a “P.S.” in the author’s voice? And once she mastered that trick, with the help of an antique typewriter, it was a short step to faking entire letters. After all, she was a close enough student of famously tart-tongued literary figures to be able to mimic them for the not-too-discerning collectibles marketplace. In no time at all, Israel was once again making a living as a writer—but under such names as Dorothy Parker, Ernest Hemingway, Lillian Hellman, Louise Brooks, George S. Kaufman and Noel Coward.

Is this an ideal story for the movies? Not exactly: the best way to appreciate the work of both distinctive writers and of clever imitations of their style is on the printed page. But a movie it has become, sharing a title with Israel’s 2004 memoir Can You Ever Forgive Me?, and it’s pretty much the best film out there at the moment.

For one thing, it stars Melissa McCarthy as Israel, and she’s so good in the part that it’s hard to believe it wasn’t written for her. (In fact she stepped in after the original star, Julianne Moore, had to quit.)

The movie has fun detailing Israel’s fakery, but it’s not quite the caper comedy you might be expecting if you saw the trailer. What makes it work in place of the literary spoofing that a film can’t entirely capture is its heartfelt portrait of a disappointed woman in a city where that can hurt the most because the possibilities are so enormous. In an early scene, Israel drags herself to a cocktail party at the swanky home of her agent (Jane Curtin) just as a way of getting a few words with her about her career possibilities. Having to listen to Tom Clancy, already making fat paychecks for turgid thrillers, regaling his admirers with how he approaches his job like factory work is nothing a blocked writer wants to hear. McCarthy has always excelled at this kind of round peg in a square hole part, and here gets to give it a more poignant edge than the comedies for which she’s better known.

To draw out this character involved in such a solitary criminal pursuit, writers Nicole Holofcener and Jeff Whitty have given her Jack Hock, an acquaintance who becomes her companion when she needs someone to share the success of her scheme with. The gay best friend is a tired cliché, but it’s hard to begrudge Richard E. Grant a role he’s having so much fun playing. That he suffers the fate of most gay men in films set in this era may be factual to the real character, but then so little else about the part is that you wonder why they bother keeping that.

That Israel’s forgeries were eventually detected and her career curtailed is no surprise, but though it renders the final third of the movie a bit grim, you manage to leave the movie with a smile on your face. The moment that will be McCarthy’s Oscar clip (there’s no doubt she’ll get a nomination) comes when she stands before a judge and manages to be both contrite and yet triumphant: illegal it may have been, but her lovingly crafted forgeries were the highlight of her literary career.