The Lion, the Witch and the Wardrobe was the first book published in what became "The Chronicles of Narnia," one of the most successful series of children's books ever written. We meet four siblings shipped out of London during the Second World War because of the bombing. Now settled in a large country house, they begin exploring - and eventually find a wardrobe that sometimes leads to another country. When all four end up there at once, they find the country shrouded in eternal winter brought on by the evil White Witch. The children play a significant part in trying to end her reign.
Reading this in 2019 (and as an adult - I first read it when I was very young), there are some significant problems with the book. It's written in what I've come to think of as "hyper-polite British English," a form of children's writing exemplified by these books and the "Swallows and Amazons" series from roughly the same period (there are undoubtedly many more, but these two series are the most famous on this continent). The language isn't precisely a problem, but it takes some adjusting to as that isn't how anyone thinks or speaks anymore (if it ever was). It's overloaded with blatant Christian allegory (which is undoubtedly not a problem for everyone). It's got a massive dose of what's now called "White Saviour complex:" here we have a land populated with intelligent talking animals and no humans (although there are many human-shaped creatures: dwarves, giants, dryads, mermaids and mermen ...) - but white children arrive, help save the world, and become the Kings and Queens. Placed there by the world's own god. What was wrong with the native population that they had to be saved by outsiders? And I've kept the best (or worst) for last. Aslan says "... For you also are not to be in the battle." "Why sir?" said Lucy. "I think -- I don't know -- but I think I could be brave enough." "That is not the point," he said. "But battles are ugly when women fight." Aside from the massive sexism, what, battles are nice and clean when only men fight? Seriously? Lewis fought at the front line in the First World War: he knew better than most how horrible war is.
I had a pretty good idea all of these problems were coming, and if you can get past them ... it's still a pretty good story. The introduction to Narnia is lovely - as silly as it seems, Lucy's initial trip through the wardrobe is charming and intriguing. And then the problems and tensions mount throughout the book to a grand climax. This is a far superior book to the later published and not nearly as well constructed "The Magician's Nephew" which is now occasionally being called the "first" book in the series. This book is a far better entry point to Narnia.