So let me try to explain to you what I can. Meet Lord Montague "Monty" D'Ysquith Navarro, Ninth Earl of Highhurst, whose mother died penniless because she had been disowned by the wealthy and powerful D'Ysquith family for running off and marrying a Spanish musician. Monty did not know he was a D'Ysquith and when he discovers this, he attempts to reunite with his estranged and strange family. They treat him as they did his mother: horribly. So in order for Monty to claim his inheritance and eventually become the Ninth Earl of Highhurst, Monty must eliminate all those in between including the Eighth Earl. That number would be eight extremely odd human, and I use the term loosely, beings.
The musical is based on 1907 novel Israel Rank: The Autobiography of a Criminal by Roy Horniman. The novel also inspired the 1949 black comedy movie Kind Hearts and Coronets. The eight roles played by Rapson were also played by one actor, Sir Alec Guinness. The family name in the movie is D'Ascoyne. The musical is based on the novel since the writers did not have rights to the 1949 movie.