Lucy Angkatell invited Hercule Poirot to lunch. To tease the great detective, her guests stage a mock murder beside the swimming pool. Unfortunately, the victim plays the scene for real. As his blood drips into the water, John Christow gasps one final word: "Henrietta". In the confusion, a gun sinks to the bottom..
Ask a dozen people to name a genius and the odds are that 'Einstein' will spring to their lips. Ask them the meaning of 'relativity' and few of them will be able to tell you what it is.