I am finding there's a certain... flavor, older fantasy has. I haven't quite nailed it down, but it reminds me of a more obscure time when fantasy books had watercolor front cover illustrations, or pen and ink over a watercolor background. It was written the year I was born, 1968, and so while it's a little younger than Madeleine L'Engle's "Wrinkle in Time," it has that same feel. Like a junior adult fiction on a spinner rack. Back when sci-fi and fantasy were pulp paperbacks, and riding that edge of being for adults and for children.
I only vaguely remembered the plot. I don't even remember the ending exactly, which is good, because it's like reading it for the first time, only invoking old, old memories of, "Oooohhhh... that's where I got that concept from." I vaguely recall it ends on a depressing note, but then again, I found so did "A Wrinkle in Time," and apparently I had a very bent way of looking at things because I don't think that has a depressing ending now. Meg lives! So does her dad!
We shall see.