If I understand correctly, you have a page that contains an iFrame that displays content from another website, but when the page loads the whole page redirects to that site??
If this is the case, the owner of the site has implemented a "frame-buster" script that detects whether or not the content is "top document"; if it isn't, then it redirects the whole page to just that content. AFAIK, there is no work-around for that. Someone else might have an idea.
If this is not the case, please clarify your question.