Many Waters, the fourth book (in publication order) of Madeline L'Engle's Time Quartet, actually takes place in the internal chronology between A Wind in the Door and A Swiftly Tilting Planet, featuring the characters 7 or so years younger than they appeared in Planet. It follows Sandy and Dennys, the "normal" kids in the family, a pair of twins who have striven to fit in with their peers.
Following Planet, it too was more enjoyable to me, as it felt much more honest in the way it dealt with the issues it explored. It followed Sandy and Dennys after they accidentally sent themselves back to antediluvian times when they meddled with their father's experiment, and wind up in Noah's camp in the year or so leading up to the flood. It dealt, very candidly and tastefully, with issues of adolescence, of growing up, of the complexity of sexual relations, of betrayal, and of hope. The version of the world it presents is fascinating, mirroring the present while preserving some of the alienness of the past.
I found it very easy to identify with the two twins, skeptics who are confronted with things beyond their experience, and I appreciated their anger at God - called "El" by Noah and his people - for drowning everyone they knew.
The science fiction elements were strongly portrayed, as was a certain element of fantasy, with seraphim, nephilim, even tiny mammoths. The portrayal of the people of the past as tiny - most reaching 4 feet in height at best - was accurate and is something not often seen in books that delve into the past.
All in all, I enjoyed the book far more than I was expecting to, and it was an excellent follow-up - or lead-in - to Planet.
Books: Still reading Stuff.
Bottles: Nothing new.
Writing: Nothing new.
Guitar: Nothing new...sigh.