Chapter 16 - "The Chamber of Secrets" - In which the students learn that exams will be held as usual, Ginny acts strangely, Harry and Ron visit Hermione in hospital, find she has the answer to the Chamber's secret (a basilisk), eavesdrop on the teachers, and learn Ginny has been taken by the monster. Lockhart attempts to flee, but Harry and Ron force him to accompany them to the Chamber via Moaning Myrtle's bathroom to rescue Ginny. They unlock the secret of the entrance. Lockhart attempts to escape by using Ron's broken wand, but it backfires and blocks the tunnel. Harry goes on alone.
A Conversation With Aragog
Harry, Ron, and Fang are picked up by [acromantulas] and carried to Aragog. Aragog explains that he was not the monster from the Chamber of Secrets, the monster that killed a girl in the bathroom. He then tells his family to devour Ron and Harry, who escape only with the help of Mr. Weasley's car.
Back in Hagrid's hut, Harry and Ron discuss the [acromantulas] and catch their breath before heading up to their [dormitory]. Just before falling asleep though, Harry realizes that the girl killed by the monster 50 years before was probably Moaning Myrtle.
The Mystery of the Monster Unfolds
At breakfast Professor McGonagall announces that the [Mandrake Restorative Draught] is almost ready, to an excited student body. Ginny comes over, scared, and tries to tell them something but is scared away by Percy.
Harry and Ron run up to the hospital wing to see Hermione, to Madam Pomfrey's displeasure. Once there, Harry finds a page of a library book in Hermione's hand, explaining the [basilisk], and figures out that it's [Slytherin's monster], and how all of the pieces fit together - including the fact that the entrance to the chamber is in [Moaning Myrtle's bathroom] - and run off to find McGonagall.
As they run to the [staffroom], Harry and Ron overhear McGonagall announcing that classes have been canceled, and hide in the staffroom wardrobe. There they listen to the staff, and learn that Ginny has been taken by [Slytherin's monster]. The teachers send Lockhart to go save her, and then leave to announce the school's closing to the students.