Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
Third Person (Limited Omniscient)
A Wrinkle in Time has a third-person narrator, but one that's hovering over Meg's head most of the time. When the kids tesser for the first time, we see it through Meg's eyes, and throughout the novel we rarely get commentary on what's happening beyond what Meg is aware of. One of the few instances of such commentary happens on Ixchel, the planet of the beasts:
[Meg] teetered on the see-saw of love and hate, and the Black Thing pushed her down into hate. "You don't even know where we are!" she cried out at her father. "Well never see Mother or the twins again! We don't know where earth is! Or even where Camazotz is! We're lost out in space! What are you going to do!" She did not realize that she was as much in the power of the Black Thing as Charles Wallace. (10.67)
Here the third-person narrator steps out of Meg's perspective for a moment to give us additional information about why Meg is acting the way she is. While on the one hand this distances from Meg, it also creates sympathy for her at a time when she's being annoying...which works to bring the reader closer to Meg in the end. Most of the time, however, the narrator stays within Meg's limitations, which means that we, as readers, learn about what's going on and why at the same time she does.