A movie I saw in the late 60's or 70's. I got the impression that it was a film version of a stage play. I don't remember much about it. It was an off-beat personality study. It had a funny one-word title. A very eccentric young man tried and failed to kill his rival for a girl with Deadly Nightshade. He tried to kill someone else who maybe mocked his eccentricities with martial arts. I think the eccentric man was played by Roddy McDowall or maybe Tom Courtnay. Or maybe not.