This diary holds memories of terrible things. Things that were covered up. Things that happened at Hogwarts School of Witchcraft and Wizardry. 
Tom Marvolo Riddle 

Harry's second year at Hogwarts is rife with fresh torments and horrors, including an outrageously stuck-up new professor, Gilderoy Lockhart, a spirit named Moaning Myrtle who haunts the girls' bathroom, and the unwanted attentions of Ron Weasley's younger sister, Ginny. 

But these seem minor when the real trouble begins, and someone or something starts turning Hogwarts students to stone. Could it be Draco Malfoy, a more poisonous rival than ever? Could it possibly be Hagrid, whose mysterious past is finally revealed? Or could it be the one everyone at Hogwarts most suspects... Harry Potter himself!