Who are Edward Laverick and Edward Carter able to fool?
At his country estate, Arthur Hilton is regaling his dinner guests of his exploits as a police officer decades earlier in Africa.  He keys in a case where he had to track down a gang of three men who were suspected of a series of murders.  He does stumble on them, but they actually end up capturing him.  Fortunately, he was able to talk his way out of that predicament, and later on tracked them down again and captured them.  One was hanged for his crimes, while the other two were sentenced to twenty years in prison.
Little does Hilton know that two of his dinner guests, Edward Laverick and Edward Carter, are the two men who he sent to prison.  They have vowed revenge, and prior to dinner, they exact it, killing Hilton.  However, they have planned it to look like a suicide on the part of the elderly aristocrat.  Initially, their plot seems successful, as the local constables who arrive to investigate the incident buy into the suicide scenario.
Hilton's nephew, Jimmy Hilton, and his girlfriend Mollie, who also happens to be the ward of the elder Hilton, become suspicious of the story told by the two men, and begin their own investigation. Their questioning leads them to arrive at the truth, and the two murderers are apprehended.
local constables