And finally, when they got out their pipes and went serenely puffing around, the very summit of glory was reached.
Then Huckleberry and Tom stood dumb and staring, and heard the stony-hearted liar reel off his serene statement, they expecting every moment that the clear sky would deliver God’s lightnings upon his head, and wondering to see how long the stroke was delayed.
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.