The second Harry Potter book.
One of the weaker ones in the series, actually.[Spoiler (click to open)]One weakness for the series was introduced: the first house elf we met is atypical. This gives us a false impression that wrong-foots us later.
But we have the fun and games of his being rescued from his awful aunt and uncle by a flying car and the Weasleys. And spends the rest of his summer at the Weasleys, and goes with them to the train station. Where he and Ron are magically shut out and take the magic car in desperation. Things do not go well. . . .
And then at school, there are more problems. Ron's younger sister Ginny has a crush on him. the new Defense Against the Dark Arts teacher is an arrogant braggart who doesn't teach much. And -- students are being petrified. Not to mention that Harry is hearing voices that no one else can hear, and people are talking about the Heir to Slytherin.
It involves a sword, Harry's being assured he would have done great in Slytherin, Harry and Ron sneaking into the Slytherin Common Room, the caretaker's deep, dark secret, a diary, and much more.