Now, I read Soul Music so I could go on and read this one.

As you’ll recall, Susan Sto Helit is Death’s granddaughter. She’s also
the Duchess of Sto Helit, but as she has philosophical problems with
being a non-working drone she’s currently supporting herself at the only
job deemed appropriate for young unmarried gently-born ladies–that is,
she’s a governess. And she has a problem. Her predecessor was a
believer in the “bogeyman” school of discipline, i.e., “If you don’t stay
in bed, the bogeyman will do thus and such!” Reality is thin on the
Discworld, and the result is that after dark the nursery is regularly
infested with one kind of bogeyman or another.

But Susan copes admirably and dispassionately; as a believer in the “iron
rod” school of discipline she simply applies an iron rod–specifically,
the fireplace poker–to all and sundry bogeymen….and then lets them go,
to spread the word that her nursery is To Be Avoided.

Meanwhile, for reasons I refuse to explain, Death is standing in for the
Hogfather this year. The Hogfather? You know–the Hogfather. Jolly old
fellow in a red suit, says “Ho, Ho, Ho,” rides in a sleigh pulled by four
giant pigs, and fills stalkings with sausages and blood pudding and toys
every Hogswatchnight. Him. For good and sufficient reasons, Death is
filling in for him this year. Consequently he’s having to shirk his
usual duties, and so Susan gets pulled in to take care of them–and Susan
Is Not Amused.

This is a book that answers a great many interesting questions, including
one great and abiding mystery: just what does the Tooth Fairy do with
all those teeth?