The Knicker-knocker

Frederick Evans is not a man people generally notice and almost friendless, keeps himself to himself. However, Frederick has one rather peculiar hobby. In the dead of night, he enjoys creeping around the neighbourhood and beyond, stealing women's lingerie from washing lines and later using the stolen lingerie to indulge in his sexual fantasies. However, during one dark, cloudy night while out knicker-knocking, Frederick sees something that presents him with an unparalleled opportunity.
Frederick sees a man murder his wife.