This is an enjoyable short story by Edgar Wallace, set in England during the 1920s. The Green Rust, his twelfth crime novel, is one of three books he published in 1919.
With him are his best friend, Kitson, and a local doctor, the Dutch van Heerden. He is murdered, stabbed to death in his sick bed in the first chapter, having just left his fortune to his niece, Oliva, whom he has never met.
But then theres the young detective, a young woman, a fortune, secret laboratories, poison, some gun play, hostages, and the list goes on...