On Harry's eleventh birthday, he learns he is a wizard from Rubeus Hagrid, Keeper of Keys and Grounds at Hogwarts School of Witchcraft and Wizardry, and enrols in Hogwarts. He befriends Ron Weasley and Hermione Granger and confronts Lord Voldemort, who is trying to regain power. In Harry's first year, he has to protect the Philosopher's Stone from Voldemort and one of his faithful followers at Hogwarts. After returning to school after summer break, students at Hogwarts are attacked by the legendary monster of the Chamber of Secrets after the Chamber is opened. Harry ends the attacks by killing a Basilisk and thwarting another attempt by Lord Voldemort to return to full strength. The following year, Harry hears he has been targeted by escaped mass murderer Sirius Black. Despite stringent security measures at Hogwarts, Harry encounters Black at the end of his third year and learns Black was framed and is actually Harry's godfather. He also learns that it was his father's old school friend Peter Pettigrew who betrayed his parents.