THE WEED THAT STRINGS THE HANGMAN'S BAG
If you're looking for an unusual series, a Flavia de Luce mystery might be a good choice. Flavia is an 11-year-old sleuth (circa 1950s) with an odd penchant for poisons and other curious activities. The mystery has a bit of an Agatha Christie feel to it, although maybe it's just the English country setting that brings that
out. But the pace of the novel is slow
and, at times, the story is confusing,
especially at the beginning, when
Flavia fakes her death.