His mouth pulled into a tight line, as though he couldn't trust himself to say more.

His mouth set in a tight line, but he did not answer her.

For a moment or two be stood absolutely still, his mouth drawn in a tight line.

He shook his head a little, moving now in a tight, short line.

The guy's eyes were hard and his mouth was a tight line.

Keep a tight line, but let him run if he really wants to go.

Instead, he merely stood and looked, his mouth a tight line.

The little she could see of his mouth showed it a tight, straight line.

Jim nodded once, his mouth set in a tight line.

With her mouth made into a tight line, she glared up at him.