When the first novel of the series,
Harry Potter and the Philosopher's Stone (published in some countries as
Harry Potter and the Sorcerer's Stone),
opens it is apparent that some significant event has taken place in the
wizarding world—an event so very remarkable, even the Muggles notice
signs of it. The full background to this event and Harry Potter's past
is revealed gradually through the series. After the introductory
chapter, the book leaps forward to a time shortly before Harry Potter's
eleventh birthday, and it is at this point that his magical background
begins to be revealed.
Harry's first contact with the wizarding world is through a half-giant,
Rubeus Hagrid, keeper of grounds and keys at Hogwarts. Hagrid reveals some of Harry's history. Harry learns that as a baby he witnessed his parents' murder by the power-obsessed Dark wizard
Lord Voldemort, who then attempted to kill him also.
For reasons not immediately revealed, the spell with which Voldemort
tried to kill Harry rebounded. Harry survived with only a
lightning-shaped scar on his forehead as a memento of the attack, and
Voldemort disappeared afterwards. As its inadvertent saviour from
Voldemort's reign of terror, Harry has become a living legend in the
wizarding world. However, at the orders of the venerable and well-known
wizard
Albus Dumbledore, the orphaned Harry had been placed in the home of his unpleasant
Muggle relatives, the Dursleys, who kept him safe, but hid his true heritage from him in hopes that he would grow up "normal".
With Hagrid's help, Harry prepares for and undertakes his first year
of study at Hogwarts. As Harry begins to explore the magical world, the
reader is introduced to many of the primary locations used throughout
the series. Harry meets most of the main characters and gains his two
closest friends:
Ron Weasley, a fun-loving member of an ancient, large, happy, but poor wizarding family, and
Hermione Granger, a gifted and very hardworking witch of non-magical parentage.
Harry also encounters the school's potions master,
Severus Snape, who displays a deep and abiding dislike for him, and the
Defence Against the Dark Arts teacher,
Quirinus Quirrell,
who later turns out to be controlled by Lord Voldemort. The plot
concludes with Harry's second confrontation with Lord Voldemort, who in
his quest for immortality, yearns to gain the power of the
Philosopher's Stone, a substance that bestows everlasting life.

The series continues with
Harry Potter and the Chamber of Secrets
describing Harry's second year at Hogwarts. He and his friends
investigate a 50-year-old mystery that appears tied to recent sinister
events at the school. Ron's younger sister,
Ginny Weasley,
enrols in her first year at Hogwarts, and finds an old notebook which
turns out to be Voldemort's diary from his school days. Ginny becomes
possessed by Voldemort through the diary and unconsciously opens the
"Chamber of Secrets," unleashing an ancient monster which begins
attacking students at Hogwarts. The novel delves into the history of
Hogwarts and a legend revolving around the Chamber that soon frightened
everyone in the school. The book also introduces a new
Defence Against the Dark Arts teacher,
Gilderoy Lockhart,
a highly cheerful, self-conceited know-it-all who later turns out to be
a fraud. For the first time, Harry realises that racial prejudice
exists in the wizarding world even before, and he learns that
Voldemort's reign of terror was often directed at wizards who were
descended from Muggles. Harry also learns that his ability to speak
Parseltongue, the language of snakes, is rare and often associated with the
Dark Arts. The novel ends after Harry saves Ginny's life by destroying a
basilisk and the enchanted diary which has been the source of the problems.