Does anyone know the name of a film which I think was black and white where people would walk on a beach / sand dune and be sucked under. They'd return with a mark or cross on the back of their neck. Probably quite a well known film but can't think for the life of me what it was called.

Thanks in advance.

Sounds like the movie,.

Invaders from Mars (53)

view trailer (http://www.youtube.com/watch?v=Ury5b-qtI1Y)

Thanks for that.