Depending on how one counts things, this is either the second or the fourth book in the Narnia series. I didn't grow up reading the Chronicles of Narnia, so don't have the attachment to them that I do for, say Dr. Doolittle. While we did read Narnia to our kids, I believe I only got bits and snatches of it. So, anyway, what I think I'm trying to say is that I'm a bit too old for this stuff on a personal level and not adequately enmeshed in it by having experienced it through the eyes of my young 'uns.
The story is ok, but didn't do a whole lot for me. After a hiatus of some years, the four Pevensie kids, Peter, Susan, Edmund and Lucy, are waiting for the train to take them back to boarding school. Suddenly, they find themselves transported from the bench on which they have all been sitting into the woods of Narnia. They have been called back, it seems, because Narnia has fallen under control of malign forces and they are required to set things aright. Something like that.
I'll eventually wade through the whole series, just so I can say I did, and also because my spouse is insistent, but I'll take my time. It's not engaging enough, so far, to capture my fancy for extended periods of time.