Funny, just when I was thinking of one of those blurred childhood memories of something you saw a short glimpse of on TV years and years ago and never found out what it was, I notice this thread, and the things you people say about that Edmund guy got me thinking that one of those blurred memories might be from the old Narnia series...
What I remember is this: a bunch of kids being inside a dark cave or suchlike, along with a big, talking animal (it might have been a beaver, but I'm actually not very sure). One boy exclaims that they've got to save [insert boy name], to which the animal answers that it is too late, as the witch has already blackened his heart and that he will never recover from that.
Judging from the little I know about Narnia, this does sound like it might be from the series, but can anyone confirm?