Holmes receives a letter from a man named Nathan Garrideb of 136 Little Ryder Street,[2] in which the writer asks for help in finding someone else who shares his unusual surname. He has been informed by an American, John Garrideb of Kansas, that if he can find another Garrideb he stands to inherit a large fortune.

The American visits Holmes and Watson at 221B Baker Street, and is not pleased that Nathan has involved a private detective. John Garrideb, who claims to be a lawyer, spins a ridiculous story about Alexander Hamilton Garrideb, a millionaire land tycoon he had met in Kansas, years earlier. Hamilton Garrideb was said to have bequeathed his $15 million estate to John, with the proviso that he find two more men of the same surname to share it with equally. John says he has come to England to seek out people with this name, having failed to find anyone in his home country. So far, he has found only Nathan.