I've just seen this! It was oddly compelling. My partner gave up on it in the first half hour, but I just HAD to see it all of the way through! As others have said, it's about three thieves on the run after stealing money that was to be sent back to the USA for destruction. What a strange yet wonderful film. It was obviously made towards the end of Jayne's career, as her star was falling...but she acts as if she was still on the A-List! But it's bottom of the barrel-ness makes it (and her performance) all the more interesting!
The movie starts off slowly, but once the thieves make an open sea break for it (with hostage in tow) and end up on a kooky island estate run by a demented older woman, things really shift gears and it becomes very (unintentionally) avant garde!
In this movie you get a way-past-her-prime Jayne doing her own thing (she truly seems to be in her own world while chaos reigns around her), an older woman with a few screws loose, a mysterious killer offing everyone one by one, Cameron Mitchell who never takes the time to wash off the blood and grime that is all over his face, a balding, monocled butler who looks like he's from a 2nd rate (3rd rate?) touring company of "SUNSET BOULEVARD", and did I mention Jayne? See Jayne dance! See Jayne in a cat fight! See Jayne roll around in her undies on a bed full of money! See Jayne in constant heat! See a hefty Jayne run wild on a strange island in nothing but a feather trimmed negligee, a black eye, and extremely bad hair! Just so strange! WOW!
I got this movie on a cheapy double bill (the mind-numbingly awful "SHE DEMONS" is the second feature) DVD. I sought it out just for "DOG EAT DOG", and I was NOT let down (the DVD was ultra cheap anyway...). I just wish someone out there would RESTORE this movie. It's wild and I think it could develop a cult following! NOT for everyone--but take a chance!