I almost gave up on this film as the TV version had very muddy sound, and I found it hard to follow at the start. I'm glad I didn't give up, as it turned out to be quite the clever little pot-boiler. I must admit to being a Graham Greene fan, and a Richard O'Sullivan fan as well. Firstly, the film: I found it a surprisingly good early fifties film, with adult themes well ahead of its time and very pleasing cinematography. I couldn't help thinking that Hitchcock himself would have had a hard time doing better with the suspense and the black and white visions of Venice. Sometimes corny and plot challenged, it remains a rather intelligent piece of post war European intrigue. Despite his young age (10) I believe that Richard O'Sullivan should have received top billing because, despite other comments on this site to the contrary, he both Starred in, and carried this film - quite a feat for one so young.