A grim set to his mouth?

[blueeye]

Can anyone help me with the following:

[FONT=&quot]He was a large man with a patrician nose, high cheekbones, intense blue eyes, and a grim set to his mouth.

Does "grim set to his mouth" refer to the expression of his mouth or what?

Thank you.
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[Ouisch]

Yes. It means that his mouth was neither smiling nor outright frowning; his lips were pursed in somewhat of a straight line, indicating that he is not outwardly happy and he is thoughtful and perhaps always expecting a bad outcome of a particular situation. If you met someone with a constant grim set to his mouth you would probably be intimidated - he would seem humorless and extremely serious.