This is the opening line of “A Scandal in Bohemia,” one of the most popular and enduring stories about the world’s favorite detective. “She” refers to Irene Adler, the closest thing to a love interest that Holmes ever had–in Arthur Conan Doyle’s original stories, at any rate (we won’t think about the subsequent movies). In “Scandal,” Adler is pitted against Holmes–and she’s depicted as quicker, cleverer, and ultimately more successful than her adversary. She was an American girl from New Jersey who, caught in a compromising position with a member of the Czech royal family, resorted to blackmail. Then Holmes is brought in, and their battle of intellects begins, including a heavy dose of intellectual flirtation.
Irene Adler is never outright labeled as Jewish, but her name and description allude to her Semitic ethnicity–so much so that the website TV Tropes uses Adler as one of their primary examples for the “Ambiguously Jewish” category. (Others who fit the bill: George Costanza on Seinfeld, Miracle Max in The Princess Bride, and the Three Stooges.)
Granted, Adler only appears in one of the original Sherlock Holmes stories–but she’s a beloved secondary character used constantly in remakes and expansions of Doyle’s fiction. Adler even has her own spin-off series, The Irene Adler Mysteries, by Carole Nelson Douglas. In “Scandal,” she also never romances Holmes outright, but their relationship is made explicit in several later versions, including both 2011’s film Sherlock Holmes: A Game of Shadows and 2012’s BBC series Sherlock.