This short film is one of the scariest I have ever seen. I caught it as a short prior to a screening of 'The Howling (1981)' back in the early 1980's in Brisbane. It was very effective as a slow build thriller and I will never forget the scene at the end with the guy, Tony played by Gene Foad, swimming out to his pet dog on the lake. It is a real shame this has disappeared. I have sought it out to no avail. Lesser feature films have been praised as classics of the genre. This really does deserve to be rereleased and seen again. The director did a TV movie, "The Appointment (1981)", which was also very unsettling. He obviously knew what he was doing and should have had a brilliant career directing thrillers. It makes me wonder how many other short films we will never get to see that are of this high quality.
This film make a huge impression on me. I rate it up with Halloween, Clownhouse, and When A Stranger Calls. I think it is that good.
Addendum- This film is finally getting a home media release by BFI Flipside on an anthology blu-ray called Short Sharp Shocks. I am very excited as I have been waiting almost 40 years to see this fantastic short film again. I urge all fans of good thrillers to watch it if you can. Waaaay better than most of the rubbish peddled to us as horror/thriller films now.