html file_get_contents() encoding issue

Question

I try to display html content file into php.

$file_to_load = "index.html";    
$html_page = file_get_contents($file_to_load);

But it's output :

�<�!�D�O�C�T�Y�P�E� �h�t�m�l�>���<�h�t�m�l�>��

And

mb_convert_encoding($html_page , 'UTF-8' , 'UTF-8');
=> "??<�!DOCTYPE html> <�html> <�head> <�title>"

I can't be rid of the "�" ! I tri different encoding like : "UTF-16 LE" (atom auto detect that on the html file), "ASCII" ...

What I'm doing wrong ? Someone have the same issue and find a solution ?