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].
[Ron] and [Harry] discuss the difficulty of getting to [Moaning Myrtle]'s bathrooom, worried about overcoming the stringent security measures in place.
[Professor McGonagall] announces during [Transfiguration] that exams will still be held, outraging the second years, and making [Ron] (and his broken [wand]) particularly nervous.
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].
While they are led to class by [Professor Lockhart], [Harry] and [Ron] convince him to let the class go on themselves - and leave the class straight for [Moaning Myrtle]'s bathroom.
[McGonagall] catches [Ron] and [Harry] in the hall, and they tell her they were trying to see [Hermione]. She is moved, and lets them go.
[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.