Julius Hersheimmer

In the 1922 novel The Secret Adversary, Julius P Hersheimmer is a wealthy American man who inherited millions from his father. After that he thought of his relatives and wanted to help them. He had an aunt Jane Hersheimmer who married a poor school teacher Amos Finn. Julius's father did not approve of the marriage and he broke off with his sister Jane thereafter.

Julius employed someone to search for the Finns and he discovered that they had both died after moving to the west of the United States. But they had left a daughter Jane Finn, Julius's cousin. Jane had had gone missing since 1915. Julius helps Tommy and Tuppence Beresford to find the latter. He had already previously contacted several investigating agencies throughout Europe--including Scotland Yard- to find his cousin.

Hersheimmer had only one photo of his cousin which he gave to an investigating officer without realizing that the officer was actually Mr Brown.

Julius is about thirty-five years old. He is described as being of "middle height, and squarely built to match his jaw", with a face that is "pugnacious but pleasant". Although he is American, he speaks with very little accent.

Julius carries a gun around with him everywhere. The gun is described as being "a murderous-looking automatic", and Julius affectionately refers to it as Little Willie.

Julius also proposes to Tuppence Beresford (née Cowley at the time) but the latter declines.

At the end of the novel, Julius hosts a supper party at the Savoy, where he gives carte blanche. After the party, he proposes to Jane, saying that he does not expect her to love him at once, but wants the right to take care of her. When she accepts, he says that he will see the archbishop about a special licence.