Synopsis
In a remote, lonely house on the marshes of the Thames estuary, Leonora Fiske, an ex-actress lives with her companion Ellen Creed. At first, a visit from Ellen's two sisters does little to suggest what lies ahead, but when the eccentric guests make themselves at home, Leonora's patience wears thin. She requests that Ellen's guests leave, but after a bitter row it is Leonora who vanishes.

The arrival of the Creed sisters' nephew Albert only adds to the mystery and suspense, as his own shadowy past complicates the recent occurrences. As he gradually pieces together the series of events which have unfolded, he must then hope that the eerie moonlit pantomime murder he stages to trap the real murderer succeeds - before he becomes the next victim.