The missing million by Edgar Wallace

Not too bad, but sort of boring, and with a disappointing ending. There's a mysterious figure who calls himself Kupie who sends letters to people to blackmail them: some pay and some commit suicide. Rich Rex Walton's first fiancée killed herself. Now he's about to marry Dora Coleman, and he receives letters threatening to take all his money. He takes it all out of the bank, but the day of his wedding he disappears. His best friend is Scotland Yard detective Jim Sepping, in love with Rex's sister Joan. Little criminal Nippy Knowles helps them. It turns out that Mr Coleman's butler is a criminal, and he gets mysteriously  killed. Lawyer Lawford Collet and Mr Coleman are killed too, both Kupie's accomplices. It's not a great surprise when Edgar reveals that Dora is Julie, the same woman that caused Nippy his time in prison. Discovering their plan to take his money, Rex had gone away. Mr Coleman was not her father at all, he was working with Kupie to steal the money. Kupie's real name was Tod Haydn, and he was working in the Coleman's home under the name Bennet. At the end it is said that Kupie killed himself in prison, and Dora who really had fallen in love with Rex is forgiven. Nothing really exciting.