A miserly old woman is found strangled in a Rotherhithe house with a passage nobody knew about, and a girl who came to England to find her mother is accused. Hume wrote The Mystery of a Hansom Cab in Melbourne in 1886, published it himself when nobody would touch it, sold the rights for fifty pounds and watched it become the bestselling detective novel of the century; he wrote a hundred and thirty more, and this is one of the better ones.