The Red Signal - An Agatha Christie Short Story

A classic Agatha Christie short story, available individually for the first time as an ebook. Sir Alington, a venerable expert of the mental condition is being pestered by the pretty, but fairly dotty Mrs. Eversleigh about the importance of the sixth sense. Soon the young man Dermot is drawn in and tells both of having something like a sixth sense, what he calls the red signal that spells danger.
He is about to tell them about the last time he had the feeling, the red signal, when he stops himself, the last time he had the signal was not then, it was earlier that very evening. But how could there be danger at a simple gathering of old friends? Will the evening's entertainment of a medium bring forth whatever impending danger that Dermot senses?