This movie, made half a century ago, now looks like an anthology of cinematic plots - throughout the movie I kept seeing in my head shots from later, and quite modern movies - where the whole plot is based on an arbitrary retelling of a scene from the movie 'North by Northwest'.
It's not a classic horror movie, but a stunningly light and fun detective story, not without touches of thriller and drama, of course. The whole narrative is made up of a handful of little things - funny scenes and lines of the main characters, fleeting plots that are still relevant support for parodies and new movies - all this creates one single story from hundreds of small stories.
Pictures like this are essential cultural baggage for someone interested in movies, so don't be put off by the long wait, this movie has been waiting 50 years as it is.