Far above the rot and vapours of the world the Sun was riding high and golden now in a serene country with floors of dazzling foam, but only a passing ghost of her could they see below, bleared, pale, giving no colour and no warmth.
There are no more uses of "serene" in the book.
Show samples from other sources
While I lie awake worrying, she sleeps serenely.
She remained serene even when he was yelling at her.