Movie-in-movie link

hello,

I'm trying to link a movie with in a movie to a button click.

I'm using
_root.mc_holder.loadMovie("mov.swf");

This obviously works fine, but I want to load a movie within an mc_holder in mov.swf

Have tried to think of ways to do this:
_root.mc_holder.loadMovie("mov.swf");
mov_one.mc_body.loadMovie("mov-in-mov.swf");

But obviously this ends up looking for mov_one on the stage not in mov.swf

Thanks for your help.